server/sensor.c

   1 /**
   2  * @file sensor.c
   3  * @brief Implementation of sensor thread
   4  * TODO: Finalise implementation
   5  */
   6
   7 #include "common.h"
   8 #include "sensor.h"
   9 #include "options.h"
  10 #include <math.h>
  11
  12 /** Array of sensors, initialised by Sensor_Init **/
  13 static Sensor g_sensors[NUMSENSORS]; //global to this file
  14 const char * g_sensor_names[NUMSENSORS] = {
  15         "analog_test0", "analog_test1",
  16         "digital_test0", "digital_test1"
  17 };
  18
  19 /**
  20  * Read a data value from a sensor; block until value is read
  21  * @param sensor_id - The ID of the sensor
  22  * @param d - DataPoint to set
  23  * @returns NULL for digital sensors when data is unchanged, otherwise d
  24  */
  25 DataPoint * GetData(SensorId sensor_id, DataPoint * d)
  26 {
  27         // switch based on the sensor_id at the moment for testing;
  28         // might be able to just directly access ADC from sensor_id?
  29         //TODO: Implement for real sensors
  30
  31
  32         //TODO: We should ensure the time is *never* allowed to change on the server if we use gettimeofday
  33         //              Another way people might think of getting the time is to count CPU cycles with clock()
  34         //              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
  35
  36         struct timeval t;
  37         gettimeofday(&t, NULL);
  38         d->time_stamp = (t.tv_sec - g_options.start_time.tv_sec) + 1e-6*(t.tv_usec - g_options.start_time.tv_usec);
  39
  40         // Make time relative
  41         //d->time_stamp.tv_sec -= g_options.start_time.tv_sec;
  42         //d->time_stamp.tv_usec -= g_options.start_time.tv_usec;
  43
  44         switch (sensor_id)
  45         {
  46                 case ANALOG_TEST0:
  47                 {
  48                         //CheckSensor( sensor_id, *sensor value*);
  49
  50                         static int count = 0;
  51                         d->value = count++;
  52                         break;
  53                 }
  54                 case ANALOG_TEST1:
  55                         d->value = (double)(rand() % 100) / 100;
  56                         break;
  57
  58                 //TODO: For digital sensors, consider only updating when sensor is actually changed
  59                 case DIGITAL_TEST0:
  60                         d->value = t.tv_sec % 2;
  61                         break;
  62                 case DIGITAL_TEST1:
  63                         d->value = (t.tv_sec+1)%2;
  64                         break;
  65                 default:
  66                         Fatal("Unknown sensor id: %d", sensor_id);
  67                         break;
  68         }
  69         usleep(100000); // simulate delay in sensor polling
  70
  71         return d;
  72 }
  73
  74 /**
  75  * Checks the sensor data for unsafe or unexpected results
  76  * @param sensor_id - The ID of the sensor
  77  *
  78 *
  79 void CheckSensor( SensorId sensor_id)
  80 {
  81         switch (sensor_id)
  82         {
  83                 case ANALOG_TEST0:
  84                 {
  85                         if( *sensor value* > ANALOG_TEST0_SAFETY)
  86                         {
  87                                 LogEx(LOGERR, GetData, Sensor analog_test0 is above the safe value);
  88                         //new log function that stops actuators?
  89                         }
  90                         //Also include a warning level?
  91                         else if( *sensor value* > ANALOG_TEST0_WARN)
  92                         {
  93                                 LogEx(LOGWARN, GetData, Sensor analog_test0);
  94                         }
  95                 }
  96         }
  97
  98
  99 */
 100
 101
 102 /**
 103  * Destroy a sensor
 104  * @param s - Sensor to destroy
 105  */
 106 void Destroy(Sensor * s)
 107 {
 108         // Maybe move the binary file into long term file storage?
 109         fclose(s->file);
 110 }
 111
 112
 113
 114 /**
 115  * Initialise a sensor
 116  * @param s - Sensor to initialise
 117  */
 118 void Init(Sensor * s, int id)
 119 {
 120         s->write_index = 0;
 121         s->id = id;
 122         s->points_written = 0;
 123         s->points_read = 0;
 124
 125         #define FILENAMESIZE 3
 126         char filename[FILENAMESIZE];
 127         if (s->id >= pow(10, FILENAMESIZE))
 128         {
 129                 Fatal("Too many sensors! FILENAMESIZE is %d; increase it and recompile.", FILENAMESIZE);
 130         }
 131
 132         pthread_mutex_init(&(s->mutex), NULL);
 133
 134         sprintf(filename, "%d", s->id);
 135         unlink(filename); //TODO: Move old files somewhere
 136
 137         s->file = fopen(filename, "a+b"); // open binary file
 138         Log(LOGDEBUG, "Initialised sensor %d; binary file is \"%s\"", id, filename);
 139 }
 140
 141
 142 /**
 143  * Run the main sensor polling loop
 144  * @param arg - Cast to Sensor* - Sensor that the thread will handle
 145  * @returns NULL (void* required to use the function with pthreads)
 146  */
 147 void * Sensor_Main(void * arg)
 148 {
 149         Sensor * s = (Sensor*)(arg);
 150
 151         while (Thread_Runstate() == RUNNING) //TODO: Exit condition
 152         {
 153                 // The sensor will write data to a buffer until it is full
 154                 // Then it will open a file and dump the buffer to the end of it.
 155                 // Rinse and repeat
 156
 157                 // The reason I've added the buffer is because locks are expensive
 158                 // But maybe it's better to just write data straight to the file
 159                 // I'd like to do some tests by changing SENSOR_DATABUFSIZ
 160
 161                 while (s->write_index < SENSOR_DATABUFSIZ)
 162                 {
 163                         DataPoint * d = &(s->buffer[s->write_index]);
 164                         if (GetData(s->id, d) == NULL)
 165                         {
 166                                 Fatal("Error collecting data");
 167                         }
 168                         s->write_index += 1;
 169                 }
 170
 171                 //Log(LOGDEBUG, "Filled buffer");
 172
 173                 // CRITICAL SECTION (no threads should be able to read/write the file at the same time)
 174                 pthread_mutex_lock(&(s->mutex));
 175                         //TODO: Valgrind complains about this fseek: "Syscall param write(buf) points to uninitialised byte(s)"
 176                         //              Not sure why, but we should find out and fix it.
 177                         fseek(s->file, 0, SEEK_END);
 178                         int amount_written = fwrite(s->buffer, sizeof(DataPoint), SENSOR_DATABUFSIZ, s->file);
 179                         if (amount_written != SENSOR_DATABUFSIZ)
 180                         {
 181                                 Fatal("Wrote %d data points and expected to write %d to \"%s\" - %s", amount_written, SENSOR_DATABUFSIZ, strerror(errno));
 182                         }
 183                         s->points_written += amount_written;
 184                         //Log(LOGDEBUG, "Wrote %d data points for sensor %d", amount_written, s->id);
 185                 pthread_mutex_unlock(&(s->mutex));
 186                 // End of critical section
 187
 188                 s->write_index = 0; // reset position in buffer
 189
 190         }
 191         Log(LOGDEBUG, "Thread for sensor %d exits", s->id);
 192         return NULL;
 193 }
 194
 195 /**
 196  * Get position in a binary sensor file with a timestamp using a binary search
 197  * @param s - Sensor to use
 198  * @param time_stamp - Timestamp
 199  * @param count - If not NULL, used to provide number of searches required
 200  * @param found - If not NULL, set to the closest DataPoint
 201  * @returns Integer giving the *closest* index in the file
 202  * TODO: Refactor or replace?
 203  */
 204 int FindTime(Sensor * s, double time_stamp, int * count, DataPoint * found)
 205 {
 206         DataPoint d;
 207
 208         int lower = 0;
 209         int upper = s->points_written - 1;
 210         int index = 0;
 211         if (count != NULL)
 212                 *count = 0;
 213
 214         while (upper - lower > 1)
 215         {
 216                 index = lower + ((upper - lower)/2);
 217
 218                 // 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!
 219                 // CRITICAL SECTION (May need to rethink how this is done, but I can't see how to do it without fseek :S)
 220                 // Regarding the suggestion that we have 2 file pointers; one for reading and one for writing:
 221                 // That seems like it will work... but we will have to be very careful and test it first
 222                 pthread_mutex_lock(&s->mutex);
 223                         fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
 224                         int amount_read = fread(&d, sizeof(DataPoint), 1, s->file);
 225                 pthread_mutex_unlock(&s->mutex);
 226
 227                 if (amount_read != 1)
 228                 {
 229                         Fatal("Couldn't read single data point from sensor %d", s->id);
 230                 }
 231
 232                 if (d.time_stamp > time_stamp)
 233                 {
 234                         upper = index;
 235                 }
 236                 else if (d.time_stamp < time_stamp)
 237                 {
 238                         lower = index;
 239                 }
 240                 if (count != NULL)
 241                         *count += 1;
 242         }
 243
 244         if (found != NULL)
 245                 *found = d;
 246
 247         return index;
 248
 249 }
 250
 251 /**
 252  * Print sensor data between two indexes in the file, using a given format
 253  * @param s - Sensor to use
 254  * @param start - Start index
 255  * @param end - End index
 256  * @param output_type - JSON, CSV or TSV output format
 257  */
 258 void PrintData(Sensor * s, int start, int end, OutputType output_type)
 259 {
 260         DataPoint buffer[SENSOR_QUERYBUFSIZ];
 261         int index = start;
 262
 263         if (output_type == JSON)
 264         {
 265                 FCGI_JSONValue("[");
 266         }
 267
 268
 269         while (index < end)
 270         {
 271                 int to_read = end - index;
 272                 if (to_read > SENSOR_QUERYBUFSIZ)
 273                 {
 274                         to_read = SENSOR_QUERYBUFSIZ;
 275                 }
 276
 277                 int amount_read = 0;
 278                 // CRITICAL SECTION
 279                 pthread_mutex_lock(&(s->mutex));
 280
 281                         fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
 282                         amount_read = fread(buffer, sizeof(DataPoint), to_read, s->file);
 283
 284                 pthread_mutex_unlock(&(s->mutex));
 285                 // End critical section
 286
 287                 if (amount_read != to_read)
 288                 {
 289                         Fatal("Failed to read %d DataPoints from sensor %d; read %d instead", to_read, s->id, amount_read);
 290                 }
 291
 292                 // Print the data
 293                 for (int i = 0; i < amount_read; ++i)
 294                 {
 295                         //TODO: Reformat?
 296                         switch (output_type)
 297                         {
 298                                 case JSON:
 299                                         FCGI_JSONValue("[%f, %f]", buffer[i].time_stamp, buffer[i].value);
 300                                         if (i+1 < amount_read)
 301                                                 FCGI_JSONValue(",");
 302                                         break;
 303                                 case CSV:
 304                                         FCGI_PrintRaw("%f,%f\n", buffer[i].time_stamp, buffer[i].value);
 305                                         break;
 306                                 case TSV:
 307                                 default:
 308                                         FCGI_PrintRaw("%f\t%f\n", buffer[i].time_stamp, buffer[i].value);
 309                                         break;
 310                         }
 311                 }
 312                 index += amount_read;
 313         }
 314
 315         if (output_type == JSON)
 316         {
 317                 FCGI_JSONValue("]");
 318         }
 319 }
 320
 321 /**
 322  * Fill buffer with most recent sensor data
 323  * TODO: This may be obselete; remove?
 324  * @param s - Sensor to use
 325  * @param buffer - Buffer to fill
 326  * @param bufsiz - Size of buffer to fill
 327  * @returns The number of DataPoints actually read
 328  */
 329 int Sensor_Query(Sensor * s, DataPoint * buffer, int bufsiz)
 330 {
 331         int amount_read = 0;
 332         //CRITICAL SECTION (Don't access file while sensor thread is writing to it!)
 333         pthread_mutex_lock(&(s->mutex));
 334
 335                 fseek(s->file, -bufsiz*sizeof(DataPoint), SEEK_END);
 336                 amount_read = fread(buffer, sizeof(DataPoint), bufsiz, s->file);
 337                 //Log(LOGDEBUG, "Read %d data points", amount_read);
 338         pthread_mutex_unlock(&(s->mutex));
 339         return amount_read;
 340 }
 341
 342 /**
 343  * Get a Sensor given an ID string
 344  * @param id_str ID string
 345  * @returns Sensor* identified by the string; NULL on error
 346  */
 347 Sensor * Sensor_Identify(const char * id_str)
 348 {
 349         char * end;
 350         // Parse string as integer
 351         int id = strtol(id_str, &end, 10);
 352         if (*end != '\0')
 353         {
 354                 return NULL;
 355         }
 356         // Bounds check
 357         if (id < 0 || id >= NUMSENSORS)
 358                 return NULL;
 359
 360
 361         Log(LOGDEBUG, "Sensor \"%s\" identified", g_sensor_names[id]);
 362         return g_sensors+id;
 363 }
 364
 365 /**
 366  * Handle a request to the sensor module
 367  * @param context - The context to work in
 368  * @param params - Parameters passed
 369  * TODO: Seriously need to write more helper functions and decrease the size of this function!
 370  */
 371 void Sensor_Handler(FCGIContext *context, char * params)
 372 {
 373         StatusCodes status = STATUS_OK;
 374
 375         OutputType output_type = JSON;
 376
 377
 378
 379         const char * key; const char * value;
 380
 381         Sensor * sensor = NULL;
 382
 383         struct timeval now;
 384         gettimeofday(&now, NULL);
 385
 386         double start_time = -1;
 387         double end_time = -1;
 388         double current_time = (now.tv_sec - g_options.start_time.tv_sec) + 1e-6*(now.tv_usec - g_options.start_time.tv_usec);
 389         bool seek_time = false;
 390         bool points_specified = false;
 391         int query_size = SENSOR_QUERYBUFSIZ;
 392         int start_index = -1;
 393         int end_index = -1;
 394
 395
 396         while ((params = FCGI_KeyPair(params, &key, &value)) != NULL)
 397         {
 398                 Log(LOGDEBUG, "Got key=%s and value=%s", key, value);
 399                 if (strcmp(key, "id") == 0)
 400                 {
 401                         if (sensor != NULL)
 402                         {
 403                                 Log(LOGERR, "Only one sensor id should be specified");
 404                                 status = STATUS_ERROR;
 405                                 break;
 406                         }
 407                         if (*value == '\0')
 408                         {
 409                                 Log(LOGERR, "No id specified.");
 410                                 status = STATUS_ERROR;
 411                                 break;
 412                         }
 413
 414                         sensor = Sensor_Identify(value);
 415                         if (sensor == NULL)
 416                         {
 417                                 Log(LOGERR, "Invalid sensor id: %s", value);
 418                                 status = STATUS_ERROR;
 419                                 break;
 420                         }
 421                 }
 422                 else if (strcmp(key, "format") == 0)
 423                 {
 424                         if (strcmp(value, "json") == 0)
 425                                 output_type = JSON;
 426                         else if (strcmp(value, "csv") == 0)
 427                                 output_type = CSV;
 428                         else if (strcmp(value, "tsv") == 0)
 429                                 output_type = TSV;
 430                 }
 431                 else if (strcmp(key, "points") == 0)
 432                 {
 433                         points_specified = true;
 434                         if (strcmp(value, "all") == 0)
 435                         {
 436                                 query_size = sensor->points_written;
 437                         }
 438                         else
 439                         {
 440                                 char * end;
 441                                 query_size = strtol(value, &end, 10);
 442                                 if (*end != '\0')
 443                                 {
 444                                         Log(LOGERR, "Require \"all\" or an integer value: %s = %s", key, value);
 445                                         status = STATUS_ERROR;
 446                                         break;
 447                                 }
 448                         }
 449
 450                 }
 451                 else if (strcmp(key, "start_time") == 0)
 452                 {
 453                         seek_time = true;
 454                         char * end;
 455                         start_time = strtod(value, &end);
 456                         if (*end != '\0')
 457                         {
 458                                 Log(LOGERR, "Require a double: %s = %s", key, value);
 459                                 status = STATUS_ERROR;
 460                                 break;
 461                         }
 462
 463                         // Treat negative values as being relative to the current time
 464                         if (start_time < 0)
 465                         {
 466                                 start_time = current_time + start_time;
 467                         }
 468                         start_time = floor(start_time);
 469                 }
 470                 else if (strcmp(key, "end_time") == 0)
 471                 {
 472                         seek_time = true;
 473                         char * end;
 474                         end_time = strtod(value, &end);
 475                         if (*end != '\0')
 476                         {
 477                                 Log(LOGERR, "Require a double: %s = %s", key, value);
 478                                 status = STATUS_ERROR;
 479                                 break;
 480                         }
 481
 482                         // Treat negative values as being relative to the current time
 483                         if (end_time < 0)
 484                         {
 485                                 end_time = current_time + end_time;
 486                         }
 487                         end_time = ceil(end_time);
 488                 }
 489                 // For backward compatability:
 490                 else if (strcmp(key, "dump") == 0)
 491                 {
 492                         output_type = TSV;
 493                         query_size = sensor->points_written+1;
 494                 }
 495                 else
 496                 {
 497                         Log(LOGERR, "Unknown key \"%s\" (value = %s)", key, value);
 498                         status = STATUS_ERROR;
 499                         break;
 500                 }
 501         }
 502
 503         if (status != STATUS_ERROR && sensor == NULL)
 504         {
 505                 Log(LOGERR, "No valid sensor id given");
 506                 status = STATUS_ERROR;
 507         }
 508
 509         if (status == STATUS_ERROR)
 510         {
 511                 FCGI_RejectJSON(context, "Invalid input parameters");
 512                 return;
 513         }
 514
 515
 516         if (seek_time)
 517         {
 518                 if (end_time < 0 && !points_specified)
 519                         end_index = sensor->points_written;
 520                 else
 521                 {
 522                         int count = 0; DataPoint d;
 523                         end_index = FindTime(sensor, end_time, &count, &d);
 524                         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);
 525                 }
 526                 if (start_time < 0)
 527                         start_time = 0;
 528                 else
 529                 {
 530                         int count = 0; DataPoint d;
 531                         start_index = FindTime(sensor, start_time, &count, &d);
 532                         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);
 533                 }
 534
 535                 if (points_specified)
 536                         end_index = start_index + query_size;
 537         }
 538         else
 539         {
 540                 start_index = sensor->points_written - query_size;
 541
 542                 end_index = sensor->points_written;
 543         }
 544
 545         if (start_index < 0)
 546         {
 547                 Log(LOGNOTE, "start_index = %d => Clamped to 0", start_index);
 548                 start_index = 0;
 549         }
 550         if (end_index > sensor->points_written)
 551         {
 552                 Log(LOGNOTE, "end_index = %d => Clamped to %d", end_index, sensor->points_written);
 553                 end_index = sensor->points_written;
 554         }
 555
 556         switch (output_type)
 557         {
 558                 case JSON:
 559                         FCGI_BeginJSON(context, status);
 560                         FCGI_JSONLong("id", sensor->id);
 561                         FCGI_JSONKey("data");
 562                         PrintData(sensor, start_index, end_index, output_type);
 563                         FCGI_EndJSON();
 564                         break;
 565                 default:
 566                         FCGI_PrintRaw("Content-type: text/plain\r\n\r\n");
 567                         PrintData(sensor, start_index, end_index, output_type);
 568                         //Force download with content-disposition
 569                         // Sam: This is cool, but I don't think we should do it
 570                         //  - letting the user view it in the browser and then save with their own filename is more flexible
 571                         //"Content-disposition: attachment;filename=%d.csv\r\n\r\n", sensor->id);
 572                         break;
 573         }
 574
 575 }
 576
 577 /**
 578  * Setup Sensors, start Sensor polling thread(s)
 579  */
 580 void Sensor_Spawn()
 581 {
 582         // start sensor threads
 583         for (int i = 0; i < NUMSENSORS; ++i)
 584         {
 585                 Init(g_sensors+i, i);
 586                 pthread_create(&(g_sensors[i].thread), NULL, Sensor_Main, (void*)(g_sensors+i));
 587         }
 588 }
 589
 590 /**
 591  * Quit Sensor loops
 592  */
 593 void Sensor_Join()
 594 {
 595         if (!Thread_Runstate())
 596         {
 597                 Fatal("This function should not be called before Thread_QuitProgram");
 598         }
 599         for (int i = 0; i < NUMSENSORS; ++i)
 600         {
 601                 pthread_join(g_sensors[i].thread, NULL);
 602                 Destroy(g_sensors+i);
 603         }
 604 }