+++ /dev/null
-/**
- * @file sensor.c
- * @purpose Implementation of sensor thread
- * TODO: Finalise implementation
- */
-
-
-#include "common.h"
-#include "sensor.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
- * @param d - DataPoint to set
- * @returns NULL on error, otherwise d
- */
-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
-
-
- //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:
- {
- static int count = 0;
- d->value = count++;
- break;
- }
- case SENSOR_TEST1:
- 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;
-}
-
-
-/**
- * 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->read_offset = 0;
- s->id = id;
-
- #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
- * @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)
-{
- 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));
- }
- //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;
-}
-
-/**
- * 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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