Merge branch 'refactor'
authorSam Moore <[email protected]>
Thu, 12 Sep 2013 15:50:44 +0000 (23:50 +0800)
committerSam Moore <[email protected]>
Thu, 12 Sep 2013 15:50:44 +0000 (23:50 +0800)
Conflicts:
server/sensor.c
server/sensor.h

Also made the resulting code compile.

BUT...
There are memory errors in the FCGI code :S

1  2 
server/common.h
server/data.c
server/fastcgi.c
server/run.sh
server/sensor.c
server/sensor.h

diff --combined server/common.h
  
  #include "log.h"
  #include "fastcgi.h"
- #include "thread.h"
  
  /**Converts a timeval to a double**/
  #define TIMEVAL_TO_DOUBLE(tv) ((tv).tv_sec + 1e-6 * ((tv).tv_usec))
  /**Takes the tv1-tv2 between two timevals and returns the result as a double*/
  #define TIMEVAL_DIFF(tv1, tv2) ((tv1).tv_sec - (tv2).tv_sec + 1e-6 * ((tv1).tv_usec - (tv2).tv_usec))
  
++
  #endif //_COMMON_H
diff --combined server/data.c
index 0000000,254b7bc..57b51ff
mode 000000,100644..100644
--- /dev/null
@@@ -1,0 -1,297 +1,299 @@@
 -      // Set write FILE*
 -      df->write_file = fopen(filename, "w");
 -      if (df->write_file == NULL)
 -      {
 -              Fatal("Error opening DataFile %s - %s", filename, strerror(errno));
 -      }
+ /**
+  * @file data.c
+  * @purpose Implementation of data handling functions; saving, loading, displaying, selecting.
+  */
+ #include "data.h"
+ #include <assert.h> //TODO: Remove asserts
+ /**
+  * One off initialisation of DataFile
+  * @param df - The DataFile
+  */
+ void Data_Init(DataFile * df)
+ {
+       // Everything is NULL
+       df->filename = NULL;
+       df->read_file = NULL;
+       df->write_file = NULL;
+ }
+ /**
+  * Initialise a DataFile from a filename; opens read/write FILE*
+  * @param df - DataFile to initialise
+  * @param filename - Name of file; overwritten if it exists
+  */
+ void Data_Open(DataFile * df, const char * filename)
+ {
+       assert(filename != NULL);
+       assert(df != NULL);
+       // Set the filename
+       df->filename = filename;
+       // Set number of DataPoints
+       df->num_points = 0; 
++
++      // Set write FILE*
++      df->write_file = fopen(filename, "w");
++      if (df->write_file == NULL)
++      {
++              Fatal("Error opening DataFile %s - %s", filename, strerror(errno));
++      }
+       
+       // Set read FILE*
+       df->read_file = fopen(filename, "r");
+       if (df->read_file == NULL)
+       {
+               Fatal("Error opening DataFile %s - %s", filename, strerror(errno));
+       }
 -void Data_Print(DataFile * df, int start_index, int end_index, DataFormat format)
++
+ }
+ /**
+  * Close a DataFile
+  * @param df - The DataFile to close
+  */
+ void Data_Close(DataFile * df)
+ {
+       assert(df != NULL);
+       //TODO: Write data to TSV?
+       // Clear the FILE*s
+       df->read_file = NULL;
+       df->write_file = NULL;
+       // Clear the filename
+       df->filename = NULL;
+ }
+ /**
+  * Save DataPoints to a DataFile
+  * @param df - The DataFile to save to
+  * @param buffer - Array of DataPoint(s) to save
+  * @param amount - Number of DataPoints in the buffer
+  */
+ void Data_Save(DataFile * df, DataPoint * buffer, int amount)
+ {
+       assert(df != NULL);
+       assert(buffer != NULL);
+       assert(amount >= 0);
+       // Go to the end of the file
+       if (fseek(df->write_file, 0, SEEK_END) < 0)
+       {
+               Fatal("Error seeking to end of DataFile %s - %s", df->filename, strerror(errno));
+       }
+       // Attempt to write the DataPoints
+       int amount_written = fwrite(buffer, sizeof(DataPoint), amount, df->write_file);
+       
+       // Check if the correct number of points were written
+       if (amount_written != amount)
+       {
+               Fatal("Wrote %d points instead of %d to DataFile %s - %s", amount_written, amount, df->filename, strerror(errno));
+       }
+       // Update number of DataPoints
+       pthread_mutex_lock(&(df->mutex));
+               df->num_points += amount_written;
+       pthread_mutex_unlock(&(df->mutex));
+       
+ }
+ /**
+  * Read DataPoints from a DataFile
+  * @param df - The DataFile to read from
+  * @param buffer - Array to fill with DataPoints
+  * @param index - Index to start reading at (inclusive)
+  * @param amount - Maximum number of DataPoints to read
+  * @returns - Actual number of points read (If smaller than amount, the end of the file was reached)
+  */
+ int Data_Read(DataFile * df, DataPoint * buffer, int index, int amount)
+ {
+       assert(df != NULL);
+       assert(buffer != NULL);
+       assert(index >= 0);
+       assert(amount > 0);
+       
+       // If we would read past the end of the file, reduce the amount of points to read
+       pthread_mutex_lock(&(df->mutex));
+               if (index + amount >= df->num_points)
+               {
+                       Log(LOGDEBUG, "Requested %d points but will only read %d to get to EOF", amount, df->num_points - index);
+                       amount = df->num_points - index;
+               }
+       pthread_mutex_unlock(&(df->mutex));
+       // Go to position in file
+       if (fseek(df->read_file, index*sizeof(DataPoint), SEEK_SET))
+       {
+               Fatal("Error seeking to position %d in DataFile %s - %s", index, df->filename, strerror(errno));
+       }
+       // Attempt to read the DataPoints
+       int amount_read = fread(buffer, sizeof(DataPoint), amount, df->read_file);
+       // Check if correct number of points were read
+       if (amount_read != amount)
+       {
+               Fatal("Read %d points instead of %d from DataFile %s - %s", amount_read, amount, df->filename, strerror(errno));
+       }
+       return amount;
+ }
+ /**
+  * Print data points between two indexes using a given format
+  * @param df - DataFile to print
+  * @param start_index - Index to start at (inclusive)
+  * @param end_index - Index to end at (inclusive)
+  * @param format - The format to use
+  */
 -void Data_PrintTimes(DataFile * df, double start_time, double end_time, DataFormat format)
++void Data_PrintByIndexes(DataFile * df, int start_index, int end_index, DataFormat format)
+ {
+       assert(df != NULL);
+       assert(start_index >= 0);
+       assert(end_index <= df->num_points-1);
+       const char * fmt_string; // Format for each data point
+       char seperator; // Character used to seperate successive data points
+       
+       // Determine what format string and seperator character to use
+       switch (format)
+       {
+               case JSON:
+                       fmt_string = "[%f,%f]";
+                       seperator = ',';
+                       // For JSON we need an opening bracket
+                       FCGI_PrintRaw("["); 
+                       break;
+               case TSV:
+                       fmt_string = "%f\t%f";
+                       seperator = '\n';
+                       break;
+       }
+       DataPoint buffer[DATA_BUFSIZ]; // Buffer
+       int index = start_index;
+       // Repeat until all DataPoints are printed
+       while (index <= end_index)
+       {
+               // Fill the buffer from the DataFile
+               int amount_read = Data_Read(df, buffer, index, DATA_BUFSIZ);
+               // Print all points in the buffer
+               for (int i = 0; i < amount_read; ++i)
+               {
+                       // Print individual DataPoint
+                       FCGI_PrintRaw(fmt_string, buffer[i].time_stamp, buffer[i].value);
+                       
+                       // Last seperator is not required
+                       if (index+1 < end_index)
+                               FCGI_PrintRaw("%c", seperator);
+                       // Advance the position in the DataFile
+                       ++index;
+               }
+       }
+       
+       switch (format)
+       {
+               case JSON:
+                       // For JSON we need a closing bracket
+                       FCGI_PrintRaw("]"); 
+                       break;
+               default:
+                       break;
+       }
+ }
+ /**
+  * Print data points between two time stamps using a given format.
+  * Prints nothing if the time stamp
+  * @param df - DataFile to print
+  * @param start_time - Time to start from (inclusive)
+  * @param end_time - Time to end at (inclusive)
+  * @param format - The format to use
+  */
 -              Data_Print(df, 0, 0, format); // Will print "empty" dataset
++void Data_PrintByTimes(DataFile * df, double start_time, double end_time, DataFormat format)
+ {
+       assert(df != NULL);
+       assert(start_time > 0);
+       assert(end_time > 0);
+       assert(end_time > start_time);
+       
+       DataPoint closest;
+       // Get starting index
+       int start_index = Data_FindByTime(df, start_time, &closest);
+       // Start time is greater than most recent time stamp
+       if (start_index >= df->num_points-1 && closest.time_stamp < start_time)
+       {
 -      Data_Print(df, start_index, end_index, format);
++              Data_PrintByIndexes(df, 0, 0, format); // Will print "empty" dataset
+               return;
+       }
+       // Get finishing index
+       int end_index = Data_FindByTime(df, end_time, &closest);
+       // Print data between the indexes
++      Data_PrintByIndexes(df, start_index, end_index, format);
+ }
+ /**
+  * Get the index of the DataPoint closest to a given time stamp
+  * @param df - DataFile to search
+  * @param time_stamp - The time stamp to search for
+  * @param closest - If not NULL, will be filled with the DataPoint chosen
+  * @returns index of DataPoint with the *closest* time stamp to that given
+  */
+ int Data_FindByTime(DataFile * df, double time_stamp, DataPoint * closest)
+ {
+       assert(df != NULL);
+       assert(time_stamp >= 0);
+       assert(closest != NULL);
+       DataPoint tmp; // Current DataPoint in binary search
+       int lower = 0; // lower index in binary search
+       pthread_mutex_lock(&(df->mutex));
+               int upper = df->num_points - 1; // upper index in binary search
+       pthread_mutex_unlock(&(df->mutex));
+       int index = 0; // current index in binary search
+       // Commence binary search:
+       while (upper - lower > 1)
+       {
+               // Pick midpoint
+               index = lower + ((upper - lower)/2);
+               // Look at DataPoint
+               if (Data_Read(df, &tmp, index, 1) != 1)
+               {
+                       Fatal("Couldn't read DataFile %s at index %d", df->filename, index);
+               }
+               // Change search interval to either half appropriately
+               if (tmp.time_stamp > time_stamp)
+               {
+                       upper = index;
+               }
+               else if (tmp.time_stamp < time_stamp)
+               {
+                       lower = index;
+               }
+       }
+       // Store closest DataPoint
+       if (closest != NULL)
+               *closest = tmp;
+       
+       return index;
+       
+ }
diff --combined server/fastcgi.c
@@@ -8,7 -8,6 +8,7 @@@
  
  #include <fcgi_stdio.h>
  #include <openssl/sha.h>
 +#include <stdarg.h>
  
  #include "common.h"
  #include "sensor.h"
@@@ -38,32 -37,23 +38,32 @@@ struct FCGIContext 
   * @param params User specified paramters: [actuators, sensors]
   */ 
  static void IdentifyHandler(FCGIContext *context, char *params) {
 -      bool identSensors = false, identActuators = false;
 -      const char *key, *value;
 +      bool ident_sensors = false, ident_actuators = false;
 +      //const char *key, *value;
-       struct timeval now;
++
        int i;
  
 -      while ((params = FCGI_KeyPair(params, &key, &value))) {
 +      FCGIValue values[2] = {{"sensors", &ident_sensors, FCGI_BOOL_T},
 +                                       {"actuators", &ident_actuators, FCGI_BOOL_T}};
 +
 +      if (!FCGI_ParseRequest(context, params, values, 2))
 +              return;
 +
 +      /*while ((params = FCGI_KeyPair(params, &key, &value))) {
                if (!strcmp(key, "sensors")) {
 -                      identSensors = !identSensors;
 +                      ident_sensors = !ident_sensors;
                } else if (!strcmp(key, "actuators")) {
 -                      identActuators = !identActuators;
 +                      ident_actuators = !ident_actuators;
                }
 -      }
 +      }*/
  
        FCGI_BeginJSON(context, STATUS_OK);
        FCGI_JSONPair("description", "MCTX3420 Server API (2013)");
        FCGI_JSONPair("build_date", __DATE__ " " __TIME__);
        FCGI_JSONLong("api_version", API_VERSION);
 -      if (identSensors) {
 +
 +      //Sensor and actuator information
 +      if (ident_sensors) {
                FCGI_JSONKey("sensors");
                FCGI_JSONValue("{\n\t\t");
                for (i = 0; i < NUMSENSORS; i++) {
@@@ -74,7 -64,7 +74,7 @@@
                }
                FCGI_JSONValue("\n\t}");
        }
 -      if (identActuators) {
 +      if (ident_actuators) {
                FCGI_JSONKey("actuators");
                FCGI_JSONValue("{\n\t\t");
                for (i = 0; i < NUMACTUATORS; i++) {
@@@ -199,87 -189,6 +199,87 @@@ char *FCGI_KeyPair(char *in, const cha
        return ptr;
  }
  
 +/**
 + * Aids in parsing request parameters. Expected keys along with their type
 + * and whether or not they're required are provided. This function will then
 + * parse the parameter string to find these keys.
 + * @param context The context to work in
 + * @param params The parameter string to be parsed
 + * @param values An array of FCGIValue's that specify expected keys
 + * @param count The number of elements in 'values'.
 + * @return true If the parameter string was parsed successfully, false otherwise.
 + *         Modes of failure include: Invalid a parsing error on the value,
 + *                                   an unknown key is specified,
 + *                                   a key/value pair is specified more than once, or
 + *                                   not all required keys were present.
 + *         If this function returns false, it is guaranteed that FCGI_RejectJSON
 + *         has already been called with the appropriate description message.
 + */
 +bool FCGI_ParseRequest(FCGIContext *context, char *params, FCGIValue values[], size_t count)
 +{
 +      const char *key, *value;
 +      char buf[BUFSIZ], *ptr;
 +      size_t i;
 +      
 +      while ((params = FCGI_KeyPair(params, &key, &value))) {
 +              for (i = 0; i < count; i++) {
 +                      if (!strcmp(key, values[i].key)) {
 +                              FCGIValue *val = &values[i];
 +
 +                              if (FCGI_RECEIVED(val->flags)) {
 +                                      snprintf(buf, BUFSIZ, "Value already specified for '%s'.", key);
 +                                      FCGI_RejectJSON(context, buf);
 +                                      return false;
 +                              }
 +                              val->flags |= FCGI_PARAM_RECEIVED;
 +
 +                              switch(FCGI_TYPE(val->flags)) {
 +                                      case FCGI_BOOL_T:
 +                                              *((bool*) val->value) = true;
 +                                              break;
 +                                      case FCGI_LONG_T:
 +                                              *((long*) val->value) = strtol(value, &ptr, 10);
 +                                              if (!*value || *ptr) {
 +                                                      snprintf(buf, BUFSIZ, "Expected int for '%s' but got '%s'", key, value);
 +                                                      FCGI_RejectJSON(context, FCGI_EscapeJSON(buf));
 +                                                      return false;
 +                                              }
 +                                              break;
 +                                      case FCGI_DOUBLE_T:
 +                                              *((double*) val->value) = strtod(value, &ptr);
 +                                              if (!*value || *ptr) {
 +                                                      snprintf(buf, BUFSIZ, "Expected float for '%s' but got '%s'", key, value);
 +                                                      FCGI_RejectJSON(context, FCGI_EscapeJSON(buf));
 +                                                      return false;
 +                                              }
 +                                              break;
 +                                      case FCGI_STRING_T:
 +                                              *((const char**) val->value) = value;
 +                                              break;
 +                                      default:
 +                                              Fatal("Invalid type %d given", FCGI_TYPE(val->flags));
 +                              }
 +                              break; //No need to search any more
 +                      }
 +              } //End for loop
 +              if (i == count) {
 +                      snprintf(buf, BUFSIZ, "Unknown key '%s' specified", key);
 +                      FCGI_RejectJSON(context, FCGI_EscapeJSON(buf));
 +                      return false;
 +              }
 +      }
 +
 +      //Check that required parameters are received
 +      for (i = 0; i < count; i++) {
 +              if (FCGI_IS_REQUIRED(values[i].flags) && !FCGI_RECEIVED(values[i].flags)) {
 +                      snprintf(buf, BUFSIZ, "Key '%s' required, but was not given.", values[i].key);
 +                      FCGI_RejectJSON(context, buf);
 +                      return false;
 +              }
 +      }
 +      return true;
 +}
 +
  /**
   * Begins a response to the client in JSON format.
   * @param context The context to work in.
@@@ -291,16 -200,20 +291,17 @@@ void FCGI_BeginJSON(FCGIContext *contex
        printf("{\r\n");
        printf("\t\"module\" : \"%s\"", context->current_module);
        FCGI_JSONLong("status", status_code);
 -
 -      // Jeremy: Should we include a timestamp in the JSON; something like this?
 -      double start_time = g_options.start_time.tv_sec + 1e-6*(g_options.start_time.tv_usec);
 +      //Time and running statistics
+       struct timeval now;
        gettimeofday(&now, NULL);
 -      double current_time = now.tv_sec + 1e-6*(now.tv_usec);
 -      FCGI_JSONDouble("start_time", start_time);
 -      FCGI_JSONDouble("current_time", current_time);
 -      FCGI_JSONDouble("running_time", current_time - start_time);
 +      FCGI_JSONDouble("start_time", TIMEVAL_TO_DOUBLE(g_options.start_time));
 +      FCGI_JSONDouble("current_time", TIMEVAL_TO_DOUBLE(now));
 +      FCGI_JSONDouble("running_time", TIMEVAL_DIFF(now, g_options.start_time));
  }
  
  /**
   * Adds a key/value pair to a JSON response. The response must have already
 - * been initiated by FCGI_BeginJSON. Note that characters are not escaped.
 + * been initiated by FCGI_BeginJSON. Special characters are not escaped.
   * @param key The key of the JSON entry
   * @param value The value associated with the key.
   */
@@@ -357,36 -270,6 +358,36 @@@ void FCGI_EndJSON(
        printf("\r\n}\r\n");
  }
  
 +/**
 + * Escapes a string so it can be used as a JSON string value.
 + * Does not support unicode specifiers in the form of \uXXXX.
 + * @param buf The string to be escaped
 + * @return The escaped string (return value == buf)
 + */
 +char *FCGI_EscapeJSON(char *buf)
 +{
 +      int length, i;
 +      length = strlen(buf);
 +      
 +      //Escape special characters. Must count down to escape properly
 +      for (i = length - 1; i >= 0; i--) {
 +              if (buf[i] < 0x20) { //Control characters
 +                      buf[i] = ' ';
 +              } else if (buf[i] == '"') {
 +                      if (i-1 >= 0 && buf[i-1] == '\\') 
 +                              i--;
 +                      else
 +                              buf[i] = '\'';
 +              } else if (buf[i] == '\\') {
 +                      if (i-1 >= 0 && buf[i-1] == '\'')
 +                              i--;
 +                      else
 +                              buf[i] = ' ';
 +              }
 +      }
 +      return buf;
 +}
 +
  /**
   * To be used when the input parameters are rejected. The return data
   * will also have debugging information provided.
@@@ -437,18 -320,8 +438,8 @@@ void * FCGI_RequestLoop (void *data
        FCGIContext context = {0};
        
        Log(LOGDEBUG, "First request...");
-       //TODO: The FCGI_Accept here is blocking. 
-       //              That means that if another thread terminates the program, this thread
-       //               will not terminate until the next request is made.
        while (FCGI_Accept() >= 0) {
  
-               if (Thread_Runstate() != RUNNING)
-               {
-                       //TODO: Yeah... deal with this better :P
-                       Log(LOGERR, "FIXME; FCGI gets request after other threads have finished.");
-                       printf("Content-type: text/plain\r\n\r\n+++OUT OF CHEESE ERROR+++\n");
-                       break;
-               }
                
                Log(LOGDEBUG, "Got request #%d", context.response_number);
                ModuleHandler module_handler = NULL;
        }
  
        Log(LOGDEBUG, "Thread exiting.");
-       Thread_QuitProgram(false);
        // NOTE: Don't call pthread_exit, because this runs in the main thread. Just return.
        return NULL;
  }
diff --combined server/run.sh
@@@ -1,6 -1,6 +1,6 @@@
  #!/bin/bash
  # Use this to quickly test run the server in valgrind
--#spawn-fcgi -p9005 -n ./valgrind.sh
++spawn-fcgi -p9005 -n ./valgrind.sh
  # Use this to run the server normally
  #./stream &
--spawn-fcgi -p9005 -n ./server
++#spawn-fcgi -p9005 -n ./server
diff --combined server/sensor.c
  
  /** Array of sensors, initialised by Sensor_Init **/
  static Sensor g_sensors[NUMSENSORS]; //global to this file
+ /** Human readable names for the sensors **/
  const char * g_sensor_names[NUMSENSORS] = {   
        "analog_test0", "analog_test1", 
        "digital_test0", "digital_test1"
  };
  
  /**
-  * Read a data value from a sensor; block until value is read
-  * @param sensor_id - The ID of the sensor
-  * @param d - DataPoint to set
-  * @returns NULL for digital sensors when data is unchanged, otherwise d
+  * One off initialisation of *all* sensors
   */
DataPoint * GetData(SensorId sensor_id, DataPoint * d)
void Sensor_Init()
  {
-       // switch based on the sensor_id at the moment for testing;
-       // might be able to just directly access ADC from sensor_id?
-       //TODO: Implement for real sensors
+       for (int i = 0; i < NUMSENSORS; ++i)
+       {
+               g_sensors[i].id = i;
+               Data_Init(&(g_sensors[i].data_file));
+               g_sensors[i].record_data = false;
+       }
+ }
  
+ /**
+  * Start a Sensor recording DataPoints
+  * @param s - The Sensor to start
+  * @param experiment_name - Prepended to DataFile filename
+  */
+ void Sensor_Start(Sensor * s, const char * experiment_name)
+ {
+       char filename[BUFSIZ];
+       if (sprintf(filename, "%s_%d", experiment_name, s->id) >= BUFSIZ)
+       {
+               Fatal("Experiment name \"%s\" too long (>%d)", experiment_name, BUFSIZ);
+       }
+       Data_Open(&(s->data_file), filename);
+               
+       pthread_create(&(s->thread), NULL, Sensor_Loop, (void*)(s));
+ }
+ /**
+  * Stop a Sensor from recording DataPoints. Blocks until it has stopped.
+  * @param s - The Sensor to stop
+  */
+ void Sensor_Stop(Sensor * s)
+ {
+       if (s->record_data)
+       {
+               s->record_data = false;
+               pthread_join(s->thread, NULL);
+               Data_Close(&(s->data_file));
+       }
+ }
+ /**
+  * Stop all Sensors
+  */
+ void Sensor_StopAll()
+ {
+       for (int i = 0; i < NUMSENSORS; ++i)
+               Sensor_Stop(g_sensors+i);
+ }
+ /**
+  * Start all Sensors
+  */
+ void Sensor_StartAll(const char * experiment_name)
+ {
+       for (int i = 0; i < NUMSENSORS; ++i)
+               Sensor_Start(g_sensors+i, experiment_name);
+ }
+ /**
+  * Read a DataPoint from a Sensor; block until value is read
+  * @param id - The ID of the sensor
+  * @param d - DataPoint to set
+  * @returns True if the DataPoint was different from the most recently recorded.
+  */
+ bool Sensor_Read(Sensor * s, DataPoint * d)
+ {
        
-       //TODO: We should ensure the time is *never* allowed to change on the server if we use gettimeofday
-       //              Another way people might think of getting the time is to count CPU cycles with clock()
-       //              But this will not work because a) CPU clock speed may change on some devices (RPi?) and b) It counts cycles used by all threads
-       
+       // Set time stamp
        struct timeval t;
        gettimeofday(&t, NULL);
        d->time_stamp = TIMEVAL_DIFF(t, g_options.start_time);
  
-       // Make time relative
-       //d->time_stamp.tv_sec -= g_options.start_time.tv_sec;
-       //d->time_stamp.tv_usec -= g_options.start_time.tv_usec;
-       
-       switch (sensor_id)
+       // Read value based on Sensor Id
+       switch (s->id)
        {
                case ANALOG_TEST0:
+                       d->value = (double)(rand() % 100) / 100;
+                       break;
+               case ANALOG_TEST1:
                {
-                       //CheckSensor( sensor_id, *sensor value*); 
-               
                        static int count = 0;
                        d->value = count++;
                        break;
                }
-               case ANALOG_TEST1:
-                       d->value = (double)(rand() % 100) / 100;
-                       break;
-       
-               //TODO: For digital sensors, consider only updating when sensor is actually changed
                case DIGITAL_TEST0:
                        d->value = t.tv_sec % 2;
                        break;
                        d->value = (t.tv_sec+1)%2;
                        break;
                default:
-                       Fatal("Unknown sensor id: %d", sensor_id);
+                       Fatal("Unknown sensor id: %d", s->id);
                        break;
        }       
        usleep(100000); // simulate delay in sensor polling
  
-       return d;
+       // Perform sanity check based on Sensor's ID and the DataPoint
+       Sensor_CheckData(s->id, d);
+       // Update latest DataPoint if necessary
+       bool result = (d->value != s->newest_data.value);
+       if (result)
+       {
+               s->newest_data.time_stamp = d->time_stamp;
+       }
+       return result;
  }
  
  /**
   * Checks the sensor data for unsafe or unexpected results 
   * @param sensor_id - The ID of the sensor
-  *
- *
- void CheckSensor( SensorId sensor_id)
+  * @param d - DataPoint to check
+  */
+ void Sensor_CheckData(SensorId id, DataPoint * d)
  {
+       //TODO: Implement
+       /*
        switch (sensor_id)
        {
                case ANALOG_TEST0:
                        }
                }
        }
-               
-       
- */    
- /**
-  * Destroy a sensor
-  * @param s - Sensor to destroy
-  */
- void Destroy(Sensor * s)
- {
-       // Maybe move the binary file into long term file storage?
-       fclose(s->file);
+       */
  }
- /**
-  * Initialise a sensor
-  * @param s - Sensor to initialise
-  */
- void Init(Sensor * s, int id)
- {
-       s->write_index = 0;
-       s->id = id;
-       s->points_written = 0;
-       s->points_read = 0;
-       #define FILENAMESIZE 3
-       char filename[FILENAMESIZE];
-       if (s->id >= pow(10, FILENAMESIZE))
-       {
-               Fatal("Too many sensors! FILENAMESIZE is %d; increase it and recompile.", FILENAMESIZE);
-       }
-       pthread_mutex_init(&(s->mutex), NULL);
                
-       sprintf(filename, "%d", s->id);
-       unlink(filename); //TODO: Move old files somewhere
-       s->file = fopen(filename, "a+b"); // open binary file
-       Log(LOGDEBUG, "Initialised sensor %d; binary file is \"%s\"", id, filename);
- }
  
  /**
-  * Run the main sensor polling loop
+  * Record data from a single Sensor; to be run in a seperate thread
   * @param arg - Cast to Sensor* - Sensor that the thread will handle
   * @returns NULL (void* required to use the function with pthreads)
   */
- void * Sensor_Main(void * arg)
+ void * Sensor_Loop(void * arg)
  {
        Sensor * s = (Sensor*)(arg);
  
-       while (Thread_Runstate() == RUNNING) //TODO: Exit condition
-       {
-               // The sensor will write data to a buffer until it is full
-               // Then it will open a file and dump the buffer to the end of it.
-               // Rinse and repeat
-               // The reason I've added the buffer is because locks are expensive
-               // But maybe it's better to just write data straight to the file
-               // I'd like to do some tests by changing SENSOR_DATABUFSIZ
-               while (s->write_index < SENSOR_DATABUFSIZ)
-               {
-                       DataPoint * d = &(s->buffer[s->write_index]);
-                       if (GetData(s->id, d) == NULL)
-                       {
-                               Fatal("Error collecting data");
-                       }
-                       s->write_index += 1;
-               }
-               //Log(LOGDEBUG, "Filled buffer");
-               // CRITICAL SECTION (no threads should be able to read/write the file at the same time)
-               pthread_mutex_lock(&(s->mutex));
-                       //TODO: Valgrind complains about this fseek: "Syscall param write(buf) points to uninitialised byte(s)"
-                       //              Not sure why, but we should find out and fix it.
-                       fseek(s->file, 0, SEEK_END);
-                       int amount_written = fwrite(s->buffer, sizeof(DataPoint), SENSOR_DATABUFSIZ, s->file);
-                       if (amount_written != SENSOR_DATABUFSIZ)
-                       {
-                               Fatal("Wrote %d data points and expected to write %d to \"%s\" - %s", amount_written, SENSOR_DATABUFSIZ, strerror(errno));
-                       }
-                       s->points_written += amount_written;
-                       //Log(LOGDEBUG, "Wrote %d data points for sensor %d", amount_written, s->id);
-               pthread_mutex_unlock(&(s->mutex));
-               // End of critical section
-               s->write_index = 0; // reset position in buffer
-               
-       }
-       Log(LOGDEBUG, "Thread for sensor %d exits", s->id);
-       return NULL; 
- }
- /**
-  * Get position in a binary sensor file with a timestamp using a binary search
-  * @param s - Sensor to use
-  * @param time_stamp - Timestamp
-  * @param count - If not NULL, used to provide number of searches required
-  * @param found - If not NULL, set to the closest DataPoint
-  * @returns Integer giving the *closest* index in the file
-  * TODO: Refactor or replace?
-  */
- int FindTime(Sensor * s, double time_stamp, int * count, DataPoint * found)
- {
-       DataPoint d;
-       int lower = 0;
-       int upper = s->points_written - 1;
-       int index = 0;
-       if (count != NULL)
-               *count = 0;     
-       while (upper - lower > 1)
+       // Until the sensor is stopped, record data points
+       while (s->record_data)
        {
-               index = lower + ((upper - lower)/2);
-               // Basically anything with fseek is critical; if we don't make it critical the sensor thread may alter data at a random point in the file!
-               // CRITICAL SECTION (May need to rethink how this is done, but I can't see how to do it without fseek :S)
-               // Regarding the suggestion that we have 2 file pointers; one for reading and one for writing:
-               // That seems like it will work... but we will have to be very careful and test it first
-               pthread_mutex_lock(&s->mutex);
-                       fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
-                       int amount_read = fread(&d, sizeof(DataPoint), 1, s->file);
-               pthread_mutex_unlock(&s->mutex);
-               
-               if (amount_read != 1)
-               {
-                       Fatal("Couldn't read single data point from sensor %d", s->id);
-               }
-               if (d.time_stamp > time_stamp)
+               DataPoint d;
+               if (Sensor_Read(s, &d)) // If new DataPoint is read:
                {
-                       upper = index;
+                       Data_Save(&(s->data_file), &d, 1); // Record it
                }
-               else if (d.time_stamp < time_stamp)
-               {
-                       lower = index;
-               }
-               if (count != NULL)
-                       *count += 1;
        }
-       if (found != NULL)
-               *found = d;
-       return index;
        
- }
- /**
-  * Print sensor data between two indexes in the file, using a given format
-  * @param s - Sensor to use
-  * @param start - Start index
-  * @param end - End index
-  * @param output_type - JSON, CSV or TSV output format
-  */
- void PrintData(Sensor * s, int start, int end, OutputType output_type)
- {
-       DataPoint buffer[SENSOR_QUERYBUFSIZ];
-       int index = start;
-       if (output_type == JSON)
-       {
-               FCGI_JSONValue("[");
-       }
-       while (index < end)
-       {
-               int to_read = end - index;
-               if (to_read > SENSOR_QUERYBUFSIZ)
-               {
-                       to_read = SENSOR_QUERYBUFSIZ;
-               }
-               int amount_read = 0;
-               // CRITICAL SECTION
-               pthread_mutex_lock(&(s->mutex));
-                       fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
-                       amount_read = fread(buffer, sizeof(DataPoint), to_read, s->file);
-               pthread_mutex_unlock(&(s->mutex));
-               // End critical section
-               if (amount_read != to_read)
-               {
-                       Fatal("Failed to read %d DataPoints from sensor %d; read %d instead", to_read, s->id, amount_read);
-               }
-               // Print the data
-               for (int i = 0; i < amount_read; ++i)
-               {
-                       //TODO: Reformat?
-                       switch (output_type)
-                       {
-                               case JSON:
-                                       FCGI_JSONValue("[%f, %f]", buffer[i].time_stamp, buffer[i].value);
-                                       if (i+1 < amount_read)
-                                               FCGI_JSONValue(",");
-                                       break;
-                               case CSV:
-                                       FCGI_PrintRaw("%f,%f\n", buffer[i].time_stamp, buffer[i].value);
-                                       break;
-                               case TSV:
-                               default:
-                                       FCGI_PrintRaw("%f\t%f\n", buffer[i].time_stamp, buffer[i].value);
-                                       break;
-                       }
-               }
-               index += amount_read;
-       }
-       if (output_type == JSON)
-       {
-               FCGI_JSONValue("]");
-       }
- }
- /**
-  * Fill buffer with most recent sensor data
-  * TODO: This may be obselete; remove?
-  * @param s - Sensor to use
-  * @param buffer - Buffer to fill
-  * @param bufsiz - Size of buffer to fill
-  * @returns The number of DataPoints actually read
-  */
- int Sensor_Query(Sensor * s, DataPoint * buffer, int bufsiz)
- {
-       int amount_read = 0;
-       //CRITICAL SECTION (Don't access file while sensor thread is writing to it!)
-       pthread_mutex_lock(&(s->mutex));
-               
-               fseek(s->file, -bufsiz*sizeof(DataPoint), SEEK_END);
-               amount_read = fread(buffer, sizeof(DataPoint), bufsiz, s->file);
-               //Log(LOGDEBUG, "Read %d data points", amount_read);            
-       pthread_mutex_unlock(&(s->mutex));
-       return amount_read;
+       // Needed to keep pthreads happy
+       return NULL;
  }
  
  /**
@@@ -362,253 -206,136 +206,139 @@@ Sensor * Sensor_Identify(const char * i
        return g_sensors+id;
  }
  
+ /**
+  * Helper: Begin sensor response in a given format
+  * @param context - the FCGIContext
+  * @param format - Format
+  * @param id - ID of sensor
+  */
+ void Sensor_BeginResponse(FCGIContext * context, SensorId id, DataFormat format)
+ {
+       // Begin response
+       switch (format)
+       {
+               case JSON:
+                       FCGI_BeginJSON(context, STATUS_OK);
+                       FCGI_JSONLong("id", id);
+                       FCGI_JSONKey("data");
+                       break;
+               default:
+                       FCGI_PrintRaw("Content-type: text/plain\r\n\r\n");
+                       break;
+       }
+ }
+ /**
+  * Helper: End sensor response in a given format
+  * @param context - the FCGIContext
+  * @param id - ID of the sensor
+  * @param format - Format
+  */
+ void Sensor_EndResponse(FCGIContext * context, SensorId id, DataFormat format)
+ {
+       // End response
+       switch (format)
+       {
+               case JSON:
+                       FCGI_EndJSON();
+                       break;
+               default:
+                       break;
+       }
+ }
  /**
   * Handle a request to the sensor module
   * @param context - The context to work in
   * @param params - Parameters passed
-  * TODO: Seriously need to write more helper functions and decrease the size of this function!
   */
  void Sensor_Handler(FCGIContext *context, char * params)
  {
-       StatusCodes status = STATUS_OK;
-       OutputType output_type = JSON;
-       
-       const char * key; const char * value;
-       Sensor * sensor = NULL;
        struct timeval now;
        gettimeofday(&now, NULL);
-       double start_time = -1;
-       double end_time = -1;
-       double current_time = TIMEVAL_DIFF(now, g_options.start_time)
-       bool seek_time = false;
-       bool points_specified = false;
-       int query_size = SENSOR_QUERYBUFSIZ;
-       int start_index = -1;
-       int end_index = -1;
-       /* //Possible use case?
-       FCGIValue values[5] = {
-               {"id", &id, FCGI_REQUIRED(FCGI_INT_T)},
-               {"format", &format, FCGI_STRING_T},
-               {"points", &points, FCGI_STRING_T},
-               {"start_time", &start_time, FCGI_DOUBLE_T},
-               {"end_time", &end_time, FCGI_DOUBLE_T}
+       double current_time = TIMEVAL_DIFF(now, g_options.start_time);
++      int id = 0;
+       double start_time = 0;
+       double end_time = current_time;
+       char * fmt_str;
+       // key/value pairs
+       FCGIValue values[] = {
 -              {"id", &id, FCGI_REQUIRED(FCGI_INT_T)}, 
++              {"id", &id, FCGI_REQUIRED(FCGI_LONG_T)}, 
+               {"format", &fmt_str, FCGI_STRING_T}, 
+               {"start_time", &start_time, FCGI_DOUBLE_T}, 
+               {"end_time", &end_time, FCGI_DOUBLE_T},
        };
-       if (!FCGI_ParseRequest(context, params, values, 5))
-               return;*/
  
-       while ((params = FCGI_KeyPair(params, &key, &value)) != NULL)
+       // enum to avoid the use of magic numbers
+       typedef enum {
+               ID,
+               FORMAT,
+               START_TIME,
+               END_TIME,
+       } SensorParams;
+       
+       // Fill values appropriately
+       if (!FCGI_ParseRequest(context, params, values, sizeof(values)))
        {
-               Log(LOGDEBUG, "Got key=%s and value=%s", key, value);
-               if (strcmp(key, "id") == 0)
-               {
-                       if (sensor != NULL)
-                       {
-                               Log(LOGERR, "Only one sensor id should be specified");
-                               status = STATUS_ERROR;
-                               break;
-                       }
-                       if (*value == '\0')
-                       {
-                               Log(LOGERR, "No id specified.");
-                               status = STATUS_ERROR;
-                               break;
-                       }
-                       sensor = Sensor_Identify(value);
-                       if (sensor == NULL)
-                       {
-                               Log(LOGERR, "Invalid sensor id: %s", value);
-                               status = STATUS_ERROR;
-                               break;
-                       }
-               }
-               else if (strcmp(key, "format") == 0)
-               {
-                       if (strcmp(value, "json") == 0)
-                               output_type = JSON;
-                       else if (strcmp(value, "csv") == 0)
-                               output_type = CSV;
-                       else if (strcmp(value, "tsv") == 0)
-                               output_type = TSV;                      
-               }
-               else if (strcmp(key, "points") == 0)
-               {
-                       points_specified = true;
-                       if (strcmp(value, "all") == 0)
-                       {
-                               query_size = sensor->points_written;
-                       }
-                       else
-                       {
-                               char * end;
-                               query_size = strtol(value, &end, 10);
-                               if (*end != '\0')
-                               {
-                                       Log(LOGERR, "Require \"all\" or an integer value: %s = %s", key, value);
-                                       status = STATUS_ERROR;
-                                       break;
-                               }
-                       }
-                       
-               }
-               else if (strcmp(key, "start_time") == 0)
-               {
-                       seek_time = true;
-                       char * end;
-                       start_time = strtod(value, &end);
-                       if (*end != '\0')
-                       {
-                               Log(LOGERR, "Require a double: %s = %s", key, value);
-                               status = STATUS_ERROR;
-                               break;
-                       }                       
-                       // Treat negative values as being relative to the current time
-                       if (start_time < 0)
-                       {
-                               start_time = current_time + start_time;
-                       }
-                       start_time = floor(start_time);
-               }
-               else if (strcmp(key, "end_time") == 0)
-               {
-                       seek_time = true;
-                       char * end;
-                       end_time = strtod(value, &end);
-                       if (*end != '\0')
-                       {
-                               Log(LOGERR, "Require a double: %s = %s", key, value);
-                               status = STATUS_ERROR;
-                               break;
-                       }       
-                       // Treat negative values as being relative to the current time
-                       if (end_time < 0)
-                       {
-                               end_time = current_time + end_time;
-                       }               
-                       end_time = ceil(end_time);
-               }
-               // For backward compatability:
-               else if (strcmp(key, "dump") == 0)
-               {
-                       output_type = TSV;
-                       query_size = sensor->points_written+1;
-               }
-               else
-               {
-                       Log(LOGERR, "Unknown key \"%s\" (value = %s)", key, value);
-                       status = STATUS_ERROR;
-                       break;
-               }               
+               // Error occured; FCGI_RejectJSON already called
+               return;
        }
  
-       if (status != STATUS_ERROR && sensor == NULL)
+       // Error checking on sensor id
+       if (id < 0 || id >= NUMSENSORS)
        {
-               Log(LOGERR, "No valid sensor id given");
-               status = STATUS_ERROR;
+               Log(LOGERR, "Invalid id %d", id);
 -              FCGI_RejectJSON(); // Whoops, I do still need this!
++              FCGI_RejectJSON(context, "Invalid id"); // Whoops, I do still need this!
        }
++      
++      DataFormat format = JSON;
  
-       if (status == STATUS_ERROR)
+       // Check if format type was specified
+       if (FCGI_RECEIVED(values[FORMAT].flags))
        {
-               FCGI_RejectJSON(context, "Invalid input parameters");
-               return;
+               if (strcmp(fmt_str, "json") == 0)
+                       format = JSON;
+               else if (strcmp(fmt_str, "tsv") == 0)
+                       format = TSV;
+               else
+                       Log(LOGERR, "Unknown format type \"%s\"", fmt_str);
        }
  
-       if (seek_time)
+       // Get Sensor
 -      Sensor * s = g_sensors[id];
++      Sensor * s = g_sensors+id;
+       
+       // Begin response
+       Sensor_BeginResponse(context, id, format);
+       
+       // If a time was specified
+       if (FCGI_RECEIVED(values[START_TIME].flags) || FCGI_RECEIVED(values[END_TIME].flags))
        {
-               if (end_time < 0 && !points_specified)
-                       end_index = sensor->points_written;
-               else
-               {
-                       int count = 0; DataPoint d;
-                       end_index = FindTime(sensor, end_time, &count, &d);
-                       Log(LOGDEBUG, "FindTime - Looked for %f; found [%f,%f] after %d iterations; sensor %d, position %d", end_time, d.time_stamp, d.value, count, sensor->id, end_index);
-               }
+               // Wrap times relative to the current time
                if (start_time < 0)
-                       start_time = 0;
-               else
-               {
-                       int count = 0; DataPoint d;
-                       start_index = FindTime(sensor, start_time, &count, &d);
-                       Log(LOGDEBUG, "FindTime - Looked for %f; found [%f,%f] after %d iterations; sensor %d, position %d", start_time, d.time_stamp, d.value, count, sensor->id, start_index);
-               }
+                       start_time += current_time;
+               if (end_time < 0)
+                       end_time += current_time;
+               // Print points by time range
+               Data_PrintByTimes(&(s->data_file), start_time, end_time, format);
  
-               if (points_specified)
-                       end_index = start_index + query_size;
-       }
-       else
-       {
-               start_index = sensor->points_written - query_size;
-               
-               end_index = sensor->points_written;
-       }
-       
-       if (start_index < 0)
-       {
-               Log(LOGNOTE, "start_index = %d => Clamped to 0", start_index);
-               start_index = 0;
        }
-       if (end_index > sensor->points_written)
+       else // No time was specified; just return a recent set of points
        {
-               Log(LOGNOTE, "end_index = %d => Clamped to %d", end_index, sensor->points_written);
-               end_index = sensor->points_written;
+               pthread_mutex_lock(&(s->data_file.mutex));
+                       int start_index = s->data_file.num_points-DATA_BUFSIZ;
+                       int end_index = s->data_file.num_points-1;
+               pthread_mutex_unlock(&(s->data_file.mutex));
+               // Print points by indexes
+               Data_PrintByIndexes(&(s->data_file), start_index, end_index, format);
        }
        
-       switch (output_type)
-       {
-               case JSON:
-                       FCGI_BeginJSON(context, status);
-                       FCGI_JSONLong("id", sensor->id);
-                       FCGI_JSONKey("data");
-                       PrintData(sensor, start_index, end_index, output_type);
-                       FCGI_EndJSON();
-                       break;
-               default:
-                       FCGI_PrintRaw("Content-type: text/plain\r\n\r\n");
-                       PrintData(sensor, start_index, end_index, output_type);
-                       //Force download with content-disposition
-                       // Sam: This is cool, but I don't think we should do it
-                       //  - letting the user view it in the browser and then save with their own filename is more flexible
-                       //"Content-disposition: attachment;filename=%d.csv\r\n\r\n", sensor->id);
-                       break;
-       }
+       // Finish response
+       Sensor_EndResponse(context, id, format);
        
  }
  
- /**
-  * Setup Sensors, start Sensor polling thread(s)
-  */
- void Sensor_Spawn()
- {
-       // start sensor threads
-       for (int i = 0; i < NUMSENSORS; ++i)
-       {
-               Init(g_sensors+i, i);
-               pthread_create(&(g_sensors[i].thread), NULL, Sensor_Main, (void*)(g_sensors+i));
-       }
- }
  
- /**
-  * Quit Sensor loops
-  */
- void Sensor_Join()
- {
-       if (!Thread_Runstate())
-       {
-               Fatal("This function should not be called before Thread_QuitProgram");
-       }
-       for (int i = 0; i < NUMSENSORS; ++i)
-       {
-               pthread_join(g_sensors[i].thread, NULL);
-               Destroy(g_sensors+i);
-       }
- }
diff --combined server/sensor.h
@@@ -6,82 -6,67 +6,66 @@@
  #ifndef _SENSOR_H
  #define _SENSOR_H
  
- /** Number of data points to keep in sensor buffers **/
- #define SENSOR_DATABUFSIZ 10
- /** Size of the query buffer. @see Sensor_Handler **/
- #define SENSOR_QUERYBUFSIZ 10
+ #include "data.h"
  
  /** Number of sensors **/
  #define NUMSENSORS 4
  
  /** Safety Values for sensors **/
+ //TODO: Probably better to use an array instead
  #define ANALOG_TEST0_SAFETY 1000
  #define ANALOG_TEST1_SAFETY 1000
  #define DIGITAL_TEST0_SAFETY 1
  #define DIGITAL_TEST1_SAFETY 1
  
  
- typedef enum SensorId {
+ typedef enum SensorId 
+ {
        ANALOG_TEST0,
        ANALOG_TEST1,
        DIGITAL_TEST0,
        DIGITAL_TEST1
  } SensorId;
  
- typedef enum
- {
-       JSON, // JSON data
-       CSV, // Comma seperated vector
-       TSV // Tab seperated vector
- } OutputType;
  
  /** Human readable names for the sensors **/
  extern const char * g_sensor_names[NUMSENSORS];
  
- /** Structure to represent data recorded by a sensor at an instant in time **/
- typedef struct
- {
-       /** Time at which data was taken **/
-       double time_stamp; 
-       /** Value of data **/
-       double value;
- } DataPoint;
  
  /** Structure to represent a sensor **/
  typedef struct
  {
        /** ID number of the sensor **/
        SensorId id;
-       /** Buffer to store data from the sensor **/
-       DataPoint buffer[SENSOR_DATABUFSIZ];
-       /** Index of last point written in the data buffer **/
-       int write_index;
-       /** Number of points read **/
-       long points_read;
-       /** Number of points written to file **/
-       long points_written;
-       /** Binary file to write data into when buffer is full **/
-       FILE * file;
-       /** Number of data points stored in file **/
-       long points_stored;
-       /** Thread running the sensor **/
+       /** DataFile to store sensor values in **/
+       DataFile data_file;
+       /** Indicates whether the Sensor should record data **/
+       bool record_data;
+       /** Thread the Sensor is running in **/
        pthread_t thread;
-       /** Mutex to protect access to stuff **/
-       pthread_mutex_t mutex;
+       /** Most recently recorded data **/
+       DataPoint newest_data;
  
--      
  } Sensor;
  
  
+ extern void Sensor_Init(); // One off initialisation of *all* sensors
+ extern void Sensor_StartAll(const char * experiment_name); // Start all Sensors recording data
+ extern void Sensor_StopAll(); // Stop all Sensors recording data
+ extern void Sensor_Start(Sensor * s, const char * experiment_name); // Start a sensor recording datas
+ extern void Sensor_Stop(Sensor * s); // Stop a Sensor from recording data
  
+ extern void * Sensor_Loop(void * args); // Main loop for a thread that handles a Sensor
+ extern bool Sensor_Read(Sensor * s, DataPoint * d); // Read a single DataPoint, indicating if it has changed since the last one
+ extern void Sensor_CheckData(SensorId id, DataPoint * d); // Check a DataPoint
+ extern Sensor * Sensor_Identify(const char * str); // Identify a Sensor from a string Id
  
- extern void Sensor_Spawn(); // Initialise sensor
- extern void Sensor_Join(); //Join sensor threads
- extern void * Sensor_Main(void * args); // main loop for sensor thread; pass a Sensor* cast to void*
+ extern void Sensor_Handler(FCGIContext *context, char * params); // Handle a FCGI request for Sensor data
  
- extern int Sensor_Query(Sensor * s, DataPoint * buffer, int bufsiz); // fill buffer with sensor data
  
- extern void Sensor_Handler(FCGIContext *context, char * params);
  
  #endif //_SENSOR_H
  

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