*/
-
+#include "common.h"
#include "sensor.h"
-#include "log.h"
#include <math.h>
+/** Array of sensors, initialised by Sensor_Init **/
+static Sensor g_sensors[NUMSENSORS]; //global to this file
+
/**
* Read a data value from a sensor; block until value is read
* @param sensor_id - The ID of the sensor
- * @returns The current value of the sensor
+ * @param d - DataPoint to set
+ * @returns NULL on error, otherwise d
*/
-DataPoint GetData(int sensor_id)
+DataPoint * GetData(int sensor_id, DataPoint * d)
{
// 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
- DataPoint d;
- //TODO: Deal with time stamps properly
- static int count = 0;
- d.time = count++;
+
+ //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
+ gettimeofday(&(d->time_stamp), NULL);
+
switch (sensor_id)
{
case SENSOR_TEST0:
- d.value = count;
+ {
+ static int count = 0;
+ d->value = count++;
break;
+ }
case SENSOR_TEST1:
- d.value = (float)(rand() % 100) / 100;
+ d->value = (float)(rand() % 100) / 100;
break;
default:
Fatal("Unknown sensor id: %d", sensor_id);
break;
}
usleep(100000); // simulate delay in sensor polling
+
return d;
}
* Initialise a sensor
* @param s - Sensor to initialise
*/
-void Sensor_Init(Sensor * s, int id)
+void Init(Sensor * s, int id)
{
s->write_index = 0;
s->read_offset = 0;
s->id = id;
- #define FILENAMESIZE 4
+ #define FILENAMESIZE 3
char filename[FILENAMESIZE];
if (s->id >= pow(10, FILENAMESIZE))
{
}
+
+
+
/**
* Run the main sensor polling loop
* @param arg - Cast to Sensor* - Sensor that the thread will handle
{
Sensor * s = (Sensor*)(arg);
- while (true) //TODO: Exit condition
+ 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.
while (s->write_index < SENSOR_DATABUFSIZ)
{
- s->buffer[s->write_index] = GetData(s->id);
+ DataPoint * d = &(s->buffer[s->write_index]);
+ if (GetData(s->id, d) == NULL)
+ {
+ Fatal("Error collecting data");
+ }
s->write_index += 1;
}
// 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));
}
- Log(LOGDEBUG, "Wrote %d data points for sensor %d", amount_written, s->id);
+ //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
}
- return NULL;
+ Log(LOGDEBUG, "Thread for sensor %d exits", s->id);
+ return NULL;
}
+/**
+ * Fill buffer with most recent sensor data
+ * @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;
+}
+
+/**
+ * Get a Sensor given an ID string
+ * @param id_str ID string
+ * @returns Sensor* identified by the string; NULL on error
+ */
+Sensor * Sensor_Identify(const char * id_str)
+{
+ char * end;
+ // Parse string as integer
+ int id = strtol(id_str, &end, 10);
+ if (*end != '\0')
+ {
+ return NULL;
+ }
+ // Bounds check
+ if (id < 0 || id > NUMSENSORS)
+ return NULL;
+
+ return g_sensors+id;
+}
+
+/**
+ * Handle a request to the sensor module
+ * @param context - The context to work in
+ * @param params - Parameters passed
+ */
+void Sensor_Handler(FCGIContext *context, char * params)
+{
+ DataPoint buffer[SENSOR_QUERYBUFSIZ];
+ StatusCodes status = STATUS_OK;
+ const char * key; const char * value;
+
+ Sensor * sensor = NULL;
+
+ while ((params = FCGI_KeyPair(params, &key, &value)) != NULL)
+ {
+ 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
+ {
+ Log(LOGERR, "Unknown key \"%s\" (value = %s)", key, value);
+ status = STATUS_ERROR;
+ break;
+ }
+ }
+
+ if (status != STATUS_ERROR && sensor == NULL)
+ {
+ Log(LOGERR, "No valid sensor id given");
+ status = STATUS_ERROR;
+ }
+
+ if (status == STATUS_ERROR)
+ {
+ FCGI_RejectJSON(context);
+ }
+ else
+ {
+
+ FCGI_BeginJSON(context, status);
+ FCGI_JSONPair(key, value); // should spit back sensor ID
+ //Log(LOGDEBUG, "Call Sensor_Query...");
+ int amount_read = Sensor_Query(sensor, buffer, SENSOR_QUERYBUFSIZ);
+ //Log(LOGDEBUG, "Read %d DataPoints", amount_read);
+ //Log(LOGDEBUG, "Produce JSON response");
+ FCGI_JSONKey("data");
+ FCGI_JSONValue("[");
+ for (int i = 0; i < amount_read; ++i)
+ {
+ //TODO: Consider; is it better to give both tv_sec and tv_usec to the client seperately, instead of combining here?
+ //NOTE: Must always use doubles; floats get rounded!
+ double time = buffer[i].time_stamp.tv_sec + 1e-6*(buffer[i].time_stamp.tv_usec);
+ FCGI_JSONValue("[%f, %f]", time, buffer[i].value);
+ if (i+1 < amount_read)
+ FCGI_JSONValue(",");
+ }
+ FCGI_JSONValue("]");
+ //Log(LOGDEBUG, "Done producing JSON response");
+ FCGI_EndJSON();
+ }
+}
+
+/**
+ * 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);
+ }
+}
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