3 * @brief Implementation of sensor thread
4 * TODO: Finalise implementation
12 /** Array of sensors, initialised by Sensor_Init **/
13 static Sensor g_sensors[NUMSENSORS]; //global to this file
14 static const char * g_sensor_names[] = {"analog_test0", "analog_test1", "digital_test0", "digital_test1"};
16 * Read a data value from a sensor; block until value is read
17 * @param sensor_id - The ID of the sensor
18 * @param d - DataPoint to set
19 * @returns NULL for digital sensors when data is unchanged, otherwise d
21 DataPoint * GetData(int sensor_id, DataPoint * d)
23 // switch based on the sensor_id at the moment for testing;
24 // might be able to just directly access ADC from sensor_id?
25 //TODO: Implement for real sensors
28 //TODO: We should ensure the time is *never* allowed to change on the server if we use gettimeofday
29 // Another way people might think of getting the time is to count CPU cycles with clock()
30 // 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
33 gettimeofday(&t, NULL);
34 d->time_stamp = (t.tv_sec - g_options.start_time.tv_sec) + 1e-6*(t.tv_usec - g_options.start_time.tv_usec);
37 //d->time_stamp.tv_sec -= g_options.start_time.tv_sec;
38 //d->time_stamp.tv_usec -= g_options.start_time.tv_usec;
49 d->value = (double)(rand() % 100) / 100;
52 //TODO: For digital sensors, consider only updating when sensor is actually changed
54 d->value = t.tv_sec % 2;
57 d->value = (t.tv_sec+1)%2;
60 Fatal("Unknown sensor id: %d", sensor_id);
63 usleep(100000); // simulate delay in sensor polling
71 * @param s - Sensor to destroy
73 void Destroy(Sensor * s)
75 // Maybe move the binary file into long term file storage?
83 * @param s - Sensor to initialise
85 void Init(Sensor * s, int id)
90 #define FILENAMESIZE 3
91 char filename[FILENAMESIZE];
92 if (s->id >= pow(10, FILENAMESIZE))
94 Fatal("Too many sensors! FILENAMESIZE is %d; increase it and recompile.", FILENAMESIZE);
97 pthread_mutex_init(&(s->mutex), NULL);
99 sprintf(filename, "%d", s->id);
100 unlink(filename); //TODO: Move old files somewhere
102 s->file = fopen(filename, "a+b"); // open binary file
103 Log(LOGDEBUG, "Initialised sensor %d; binary file is \"%s\"", id, filename);
111 * Run the main sensor polling loop
112 * @param arg - Cast to Sensor* - Sensor that the thread will handle
113 * @returns NULL (void* required to use the function with pthreads)
115 void * Sensor_Main(void * arg)
117 Sensor * s = (Sensor*)(arg);
119 while (Thread_Runstate() == RUNNING) //TODO: Exit condition
121 // The sensor will write data to a buffer until it is full
122 // Then it will open a file and dump the buffer to the end of it.
125 // The reason I've added the buffer is because locks are expensive
126 // But maybe it's better to just write data straight to the file
127 // I'd like to do some tests by changing SENSOR_DATABUFSIZ
129 while (s->write_index < SENSOR_DATABUFSIZ)
131 DataPoint * d = &(s->buffer[s->write_index]);
132 if (GetData(s->id, d) == NULL)
134 Fatal("Error collecting data");
139 //Log(LOGDEBUG, "Filled buffer");
141 // CRITICAL SECTION (no threads should be able to read/write the file at the same time)
142 pthread_mutex_lock(&(s->mutex));
143 //TODO: Valgrind complains about this fseek: "Syscall param write(buf) points to uninitialised byte(s)"
144 // Not sure why, but we should find out and fix it.
145 fseek(s->file, 0, SEEK_END);
146 int amount_written = fwrite(s->buffer, sizeof(DataPoint), SENSOR_DATABUFSIZ, s->file);
147 if (amount_written != SENSOR_DATABUFSIZ)
149 Fatal("Wrote %d data points and expected to write %d to \"%s\" - %s", amount_written, SENSOR_DATABUFSIZ, strerror(errno));
151 //Log(LOGDEBUG, "Wrote %d data points for sensor %d", amount_written, s->id);
152 pthread_mutex_unlock(&(s->mutex));
153 // End of critical section
155 s->write_index = 0; // reset position in buffer
158 Log(LOGDEBUG, "Thread for sensor %d exits", s->id);
163 * Fill buffer with most recent sensor data
164 * @param s - Sensor to use
165 * @param buffer - Buffer to fill
166 * @param bufsiz - Size of buffer to fill
167 * @returns The number of DataPoints actually read
169 int Sensor_Query(Sensor * s, DataPoint * buffer, int bufsiz)
172 //CRITICAL SECTION (Don't access file while sensor thread is writing to it!)
173 pthread_mutex_lock(&(s->mutex));
175 fseek(s->file, -bufsiz*sizeof(DataPoint), SEEK_END);
176 amount_read = fread(buffer, sizeof(DataPoint), bufsiz, s->file);
177 //Log(LOGDEBUG, "Read %d data points", amount_read);
178 pthread_mutex_unlock(&(s->mutex));
183 * Get a Sensor given an ID string
184 * @param id_str ID string
185 * @returns Sensor* identified by the string; NULL on error
187 Sensor * Sensor_Identify(const char * id_str)
190 // Parse string as integer
191 int id = strtol(id_str, &end, 10);
197 if (id < 0 || id >= NUMSENSORS)
201 Log(LOGDEBUG, "Sensor \"%s\" identified", g_sensor_names[id]);
206 * Handle a request to the sensor module
207 * @param context - The context to work in
208 * @param params - Parameters passed
210 void Sensor_Handler(FCGIContext *context, char * params)
212 DataPoint buffer[SENSOR_QUERYBUFSIZ];
213 StatusCodes status = STATUS_OK;
215 enum {DEFAULT, DUMP} operation = DEFAULT;
217 const char * key; const char * value;
219 Sensor * sensor = NULL;
221 while ((params = FCGI_KeyPair(params, &key, &value)) != NULL)
223 Log(LOGDEBUG, "Got key=%s and value=%s", key, value);
224 if (strcmp(key, "id") == 0)
228 Log(LOGERR, "Only one sensor id should be specified");
229 status = STATUS_ERROR;
234 Log(LOGERR, "No id specified.");
235 status = STATUS_ERROR;
239 sensor = Sensor_Identify(value);
242 Log(LOGERR, "Invalid sensor id: %s", value);
243 status = STATUS_ERROR;
247 else if (strcmp(key, "dump") == 0)
249 if (operation != DEFAULT)
251 Log(LOGERR, "Operation already specified!");
252 status = STATUS_ERROR;
259 Log(LOGERR, "Unknown key \"%s\" (value = %s)", key, value);
260 status = STATUS_ERROR;
265 if (status != STATUS_ERROR && sensor == NULL)
267 Log(LOGERR, "No valid sensor id given");
268 status = STATUS_ERROR;
271 if (status == STATUS_ERROR)
273 FCGI_RejectJSON(context);
281 FCGI_PrintRaw("Content-type: text/plain\r\n\r\n");
283 pthread_mutex_lock(&(sensor->mutex));
284 fseek(sensor->file, 0, SEEK_SET);
288 amount_read = fread(buffer, sizeof(DataPoint), SENSOR_QUERYBUFSIZ, sensor->file);
289 for (int i = 0; i < amount_read; ++i)
291 FCGI_PrintRaw("%f\t%f\n", buffer[i].time_stamp, buffer[i].value);
295 while (amount_read == SENSOR_QUERYBUFSIZ);
296 pthread_mutex_unlock(&(sensor->mutex));
297 // end critical section
302 FCGI_BeginJSON(context, status);
303 FCGI_JSONPair(key, value); // should spit back sensor ID
304 //Log(LOGDEBUG, "Call Sensor_Query...");
305 int amount_read = Sensor_Query(sensor, buffer, SENSOR_QUERYBUFSIZ);
306 //Log(LOGDEBUG, "Read %d DataPoints", amount_read);
307 //Log(LOGDEBUG, "Produce JSON response");
308 FCGI_JSONKey("data");
310 for (int i = 0; i < amount_read; ++i)
312 //TODO: Consider; is it better to give both tv_sec and tv_usec to the client seperately, instead of combining here?
314 FCGI_JSONValue("[%f, %f]", buffer[i].time_stamp, buffer[i].value);
315 if (i+1 < amount_read)
319 //Log(LOGDEBUG, "Done producing JSON response");
327 * Setup Sensors, start Sensor polling thread(s)
331 // start sensor threads
332 for (int i = 0; i < NUMSENSORS; ++i)
334 Init(g_sensors+i, i);
335 pthread_create(&(g_sensors[i].thread), NULL, Sensor_Main, (void*)(g_sensors+i));
344 if (!Thread_Runstate())
346 Fatal("This function should not be called before Thread_QuitProgram");
348 for (int i = 0; i < NUMSENSORS; ++i)
350 pthread_join(g_sensors[i].thread, NULL);
351 Destroy(g_sensors+i);