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         "analog_fail0", "digital_test0",
  17         "digital_test1", "digital_fail0"
  18 };
  19
  20 /**
  21  * Checks the sensor data for unsafe or unexpected results
  22  * @param sensor_id - The ID of the sensor
  23  * @param value - The value of the sensor to check
  24  */
  25 void CheckSensor( SensorId sensor_id, double value)
  26 {
  27         switch (sensor_id)
  28         {
  29                 case ANALOG_FAIL0:
  30                 {
  31                         if( value > ANALOG_FAIL0_SAFETY || value < ANALOG_FAIL0_MIN_SAFETY)
  32                         {
  33                                 Log(LOGERR, "Sensor analog_fail0 is above or below its safety value of %d or %d\n", ANALOG_FAIL0_SAFETY, ANALOG_FAIL0_MIN_SAFETY);
  34                         //new function that stops actuators?
  35                         }
  36                         else if( value > ANALOG_FAIL0_WARN || value < ANALOG_FAIL0_MIN_WARN)
  37                         {
  38                                 Log(LOGWARN, "Sensor analog_test0 is above or below its warning value of %d or %d\n", ANALOG_FAIL0_WARN, ANALOG_FAIL0_MIN_WARN);
  39                         }
  40                         break;
  41                 }
  42                 case DIGITAL_FAIL0:
  43                 {
  44                         if( value != 0 && value != 1)
  45                         {
  46                                 Log(LOGERR, "Sensor digital_fail0 is not 0 or 1\n");
  47                         }
  48                         break;
  49                 }
  50                 default:
  51                 {
  52                 //So it doesn't complain about the missing cases - in practice we will need all sensors to be checked as above, no need to include a default as we should only pass valid sensor_id's; unless for some reason we have a sensor we don't need to check (but then why would you pass to this function in the first place :P)
  53                 }
  54         }
  55 }
  56
  57 /**
  58  * Read a data value from a sensor; block until value is read
  59  * @param sensor_id - The ID of the sensor
  60  * @param d - DataPoint to set
  61  * @returns NULL for digital sensors when data is unchanged, otherwise d
  62  */
  63 DataPoint * GetData(SensorId sensor_id, DataPoint * d)
  64 {
  65         // switch based on the sensor_id at the moment for testing;
  66         // might be able to just directly access ADC from sensor_id?
  67         //TODO: Implement for real sensors
  68
  69
  70         //TODO: We should ensure the time is *never* allowed to change on the server if we use gettimeofday
  71         //              Another way people might think of getting the time is to count CPU cycles with clock()
  72         //              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
  73
  74         struct timeval t;
  75         gettimeofday(&t, NULL);
  76         d->time_stamp = (t.tv_sec - g_options.start_time.tv_sec) + 1e-6*(t.tv_usec - g_options.start_time.tv_usec);
  77
  78         // Make time relative
  79         //d->time_stamp.tv_sec -= g_options.start_time.tv_sec;
  80         //d->time_stamp.tv_usec -= g_options.start_time.tv_usec;
  81
  82         switch (sensor_id)
  83         {
  84                 case ANALOG_TEST0:
  85                 {
  86                         static int count = 0;
  87                         d->value = count++;
  88                         break;
  89                 }
  90                 case ANALOG_TEST1:
  91                         d->value = (double)(rand() % 100) / 100;
  92                         break;
  93                 case ANALOG_FAIL0:
  94                         d->value = (double)(rand() % 6) * -( rand() % 2) / ( rand() % 100 + 1);
  95                         //Gives a value between -5 and 5
  96                         CheckSensor(sensor_id, d->value);
  97                         break;
  98                 //TODO: For digital sensors, consider only updating when sensor is actually changed
  99                 case DIGITAL_TEST0:
 100                         d->value = t.tv_sec % 2;
 101                         break;
 102                 case DIGITAL_TEST1:
 103                         d->value = (t.tv_sec+1)%2;
 104                         break;
 105                 case DIGITAL_FAIL0:
 106                         if( rand() % 100 > 98)
 107                                 d->value = 2;
 108                         d->value = rand() % 2;
 109                         //Gives 0 or 1 or a 2 every 1/100 times
 110                         CheckSensor(sensor_id, d->value);
 111                         break;
 112                 default:
 113                         Fatal("Unknown sensor id: %d", sensor_id);
 114                         break;
 115         }
 116         usleep(100000); // simulate delay in sensor polling
 117
 118         return d;
 119 }
 120
 121 /**
 122  * Destroy a sensor
 123  * @param s - Sensor to destroy
 124  */
 125 void Destroy(Sensor * s)
 126 {
 127         // Maybe move the binary file into long term file storage?
 128         fclose(s->file);
 129 }
 130
 131
 132
 133 /**
 134  * Initialise a sensor
 135  * @param s - Sensor to initialise
 136  */
 137 void Init(Sensor * s, int id)
 138 {
 139         s->write_index = 0;
 140         s->id = id;
 141         s->points_written = 0;
 142         s->points_read = 0;
 143
 144         #define FILENAMESIZE 3
 145         char filename[FILENAMESIZE];
 146         if (s->id >= pow(10, FILENAMESIZE))
 147         {
 148                 Fatal("Too many sensors! FILENAMESIZE is %d; increase it and recompile.", FILENAMESIZE);
 149         }
 150
 151         pthread_mutex_init(&(s->mutex), NULL);
 152
 153         sprintf(filename, "%d", s->id);
 154         unlink(filename); //TODO: Move old files somewhere
 155
 156         s->file = fopen(filename, "a+b"); // open binary file
 157         Log(LOGDEBUG, "Initialised sensor %d; binary file is \"%s\"", id, filename);
 158 }
 159
 160
 161 /**
 162  * Run the main sensor polling loop
 163  * @param arg - Cast to Sensor* - Sensor that the thread will handle
 164  * @returns NULL (void* required to use the function with pthreads)
 165  */
 166 void * Sensor_Main(void * arg)
 167 {
 168         Sensor * s = (Sensor*)(arg);
 169
 170         while (Thread_Runstate() == RUNNING) //TODO: Exit condition
 171         {
 172                 // The sensor will write data to a buffer until it is full
 173                 // Then it will open a file and dump the buffer to the end of it.
 174                 // Rinse and repeat
 175
 176                 // The reason I've added the buffer is because locks are expensive
 177                 // But maybe it's better to just write data straight to the file
 178                 // I'd like to do some tests by changing SENSOR_DATABUFSIZ
 179
 180                 while (s->write_index < SENSOR_DATABUFSIZ)
 181                 {
 182                         DataPoint * d = &(s->buffer[s->write_index]);
 183                         if (GetData(s->id, d) == NULL)
 184                         {
 185                                 Fatal("Error collecting data");
 186                         }
 187                         s->write_index += 1;
 188                 }
 189
 190                 //Log(LOGDEBUG, "Filled buffer");
 191
 192                 // CRITICAL SECTION (no threads should be able to read/write the file at the same time)
 193                 pthread_mutex_lock(&(s->mutex));
 194                         //TODO: Valgrind complains about this fseek: "Syscall param write(buf) points to uninitialised byte(s)"
 195                         //              Not sure why, but we should find out and fix it.
 196                         fseek(s->file, 0, SEEK_END);
 197                         int amount_written = fwrite(s->buffer, sizeof(DataPoint), SENSOR_DATABUFSIZ, s->file);
 198                         if (amount_written != SENSOR_DATABUFSIZ)
 199                         {
 200                                 Fatal("Wrote %d data points and expected to write %d to \"%s\" - %s", amount_written, SENSOR_DATABUFSIZ, strerror(errno));
 201                         }
 202                         s->points_written += amount_written;
 203                         //Log(LOGDEBUG, "Wrote %d data points for sensor %d", amount_written, s->id);
 204                 pthread_mutex_unlock(&(s->mutex));
 205                 // End of critical section
 206
 207                 s->write_index = 0; // reset position in buffer
 208
 209         }
 210         Log(LOGDEBUG, "Thread for sensor %d exits", s->id);
 211         return NULL;
 212 }
 213
 214 /**
 215  * Get position in a binary sensor file with a timestamp using a binary search
 216  * @param s - Sensor to use
 217  * @param time_stamp - Timestamp
 218  * @param count - If not NULL, used to provide number of searches required
 219  * @param found - If not NULL, set to the closest DataPoint
 220  * @returns Integer giving the *closest* index in the file
 221  * TODO: Refactor or replace?
 222  */
 223 int FindTime(Sensor * s, double time_stamp, int * count, DataPoint * found)
 224 {
 225         DataPoint d;
 226
 227         int lower = 0;
 228         int upper = s->points_written - 1;
 229         int index = 0;
 230         if (count != NULL)
 231                 *count = 0;
 232
 233         while (upper - lower > 1)
 234         {
 235                 index = lower + ((upper - lower)/2);
 236
 237                 // 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!
 238                 // CRITICAL SECTION (May need to rethink how this is done, but I can't see how to do it without fseek :S)
 239                 // Regarding the suggestion that we have 2 file pointers; one for reading and one for writing:
 240                 // That seems like it will work... but we will have to be very careful and test it first
 241                 pthread_mutex_lock(&s->mutex);
 242                         fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
 243                         int amount_read = fread(&d, sizeof(DataPoint), 1, s->file);
 244                 pthread_mutex_unlock(&s->mutex);
 245
 246                 if (amount_read != 1)
 247                 {
 248                         Fatal("Couldn't read single data point from sensor %d", s->id);
 249                 }
 250
 251                 if (d.time_stamp > time_stamp)
 252                 {
 253                         upper = index;
 254                 }
 255                 else if (d.time_stamp < time_stamp)
 256                 {
 257                         lower = index;
 258                 }
 259                 if (count != NULL)
 260                         *count += 1;
 261         }
 262
 263         if (found != NULL)
 264                 *found = d;
 265
 266         return index;
 267
 268 }
 269
 270 /**
 271  * Print sensor data between two indexes in the file, using a given format
 272  * @param s - Sensor to use
 273  * @param start - Start index
 274  * @param end - End index
 275  * @param output_type - JSON, CSV or TSV output format
 276  */
 277 void PrintData(Sensor * s, int start, int end, OutputType output_type)
 278 {
 279         DataPoint buffer[SENSOR_QUERYBUFSIZ];
 280         int index = start;
 281
 282         if (output_type == JSON)
 283         {
 284                 FCGI_JSONValue("[");
 285         }
 286
 287
 288         while (index < end)
 289         {
 290                 int to_read = end - index;
 291                 if (to_read > SENSOR_QUERYBUFSIZ)
 292                 {
 293                         to_read = SENSOR_QUERYBUFSIZ;
 294                 }
 295
 296                 int amount_read = 0;
 297                 // CRITICAL SECTION
 298                 pthread_mutex_lock(&(s->mutex));
 299
 300                         fseek(s->file, index*sizeof(DataPoint), SEEK_SET);
 301                         amount_read = fread(buffer, sizeof(DataPoint), to_read, s->file);
 302
 303                 pthread_mutex_unlock(&(s->mutex));
 304                 // End critical section
 305
 306                 if (amount_read != to_read)
 307                 {
 308                         Fatal("Failed to read %d DataPoints from sensor %d; read %d instead", to_read, s->id, amount_read);
 309                 }
 310
 311                 // Print the data
 312                 for (int i = 0; i < amount_read; ++i)
 313                 {
 314                         //TODO: Reformat?
 315                         switch (output_type)
 316                         {
 317                                 case JSON:
 318                                         FCGI_JSONValue("[%f, %f]", buffer[i].time_stamp, buffer[i].value);
 319                                         if (i+1 < amount_read)
 320                                                 FCGI_JSONValue(",");
 321                                         break;
 322                                 case CSV:
 323                                         FCGI_PrintRaw("%f,%f\n", buffer[i].time_stamp, buffer[i].value);
 324                                         break;
 325                                 case TSV:
 326                                 default:
 327                                         FCGI_PrintRaw("%f\t%f\n", buffer[i].time_stamp, buffer[i].value);
 328                                         break;
 329                         }
 330                 }
 331                 index += amount_read;
 332         }
 333
 334         if (output_type == JSON)
 335         {
 336                 FCGI_JSONValue("]");
 337         }
 338 }
 339
 340 /**
 341  * Fill buffer with most recent sensor data
 342  * TODO: This may be obselete; remove?
 343  * @param s - Sensor to use
 344  * @param buffer - Buffer to fill
 345  * @param bufsiz - Size of buffer to fill
 346  * @returns The number of DataPoints actually read
 347  */
 348 int Sensor_Query(Sensor * s, DataPoint * buffer, int bufsiz)
 349 {
 350         int amount_read = 0;
 351         //CRITICAL SECTION (Don't access file while sensor thread is writing to it!)
 352         pthread_mutex_lock(&(s->mutex));
 353
 354                 fseek(s->file, -bufsiz*sizeof(DataPoint), SEEK_END);
 355                 amount_read = fread(buffer, sizeof(DataPoint), bufsiz, s->file);
 356                 //Log(LOGDEBUG, "Read %d data points", amount_read);
 357         pthread_mutex_unlock(&(s->mutex));
 358         return amount_read;
 359 }
 360
 361 /**
 362  * Get a Sensor given an ID string
 363  * @param id_str ID string
 364  * @returns Sensor* identified by the string; NULL on error
 365  */
 366 Sensor * Sensor_Identify(const char * id_str)
 367 {
 368         char * end;
 369         // Parse string as integer
 370         int id = strtol(id_str, &end, 10);
 371         if (*end != '\0')
 372         {
 373                 return NULL;
 374         }
 375         // Bounds check
 376         if (id < 0 || id >= NUMSENSORS)
 377                 return NULL;
 378
 379
 380         Log(LOGDEBUG, "Sensor \"%s\" identified", g_sensor_names[id]);
 381         return g_sensors+id;
 382 }
 383
 384 /**
 385  * Handle a request to the sensor module
 386  * @param context - The context to work in
 387  * @param params - Parameters passed
 388  * TODO: Seriously need to write more helper functions and decrease the size of this function!
 389  */
 390 void Sensor_Handler(FCGIContext *context, char * params)
 391 {
 392         StatusCodes status = STATUS_OK;
 393
 394         OutputType output_type = JSON;
 395
 396
 397
 398         const char * key; const char * value;
 399
 400         Sensor * sensor = NULL;
 401
 402         struct timeval now;
 403         gettimeofday(&now, NULL);
 404
 405         double start_time = -1;
 406         double end_time = -1;
 407         double current_time = (now.tv_sec - g_options.start_time.tv_sec) + 1e-6*(now.tv_usec - g_options.start_time.tv_usec);
 408         bool seek_time = false;
 409         bool points_specified = false;
 410         int query_size = SENSOR_QUERYBUFSIZ;
 411         int start_index = -1;
 412         int end_index = -1;
 413
 414
 415         while ((params = FCGI_KeyPair(params, &key, &value)) != NULL)
 416         {
 417                 Log(LOGDEBUG, "Got key=%s and value=%s", key, value);
 418                 if (strcmp(key, "id") == 0)
 419                 {
 420                         if (sensor != NULL)
 421                         {
 422                                 Log(LOGERR, "Only one sensor id should be specified");
 423                                 status = STATUS_ERROR;
 424                                 break;
 425                         }
 426                         if (*value == '\0')
 427                         {
 428                                 Log(LOGERR, "No id specified.");
 429                                 status = STATUS_ERROR;
 430                                 break;
 431                         }
 432
 433                         sensor = Sensor_Identify(value);
 434                         if (sensor == NULL)
 435                         {
 436                                 Log(LOGERR, "Invalid sensor id: %s", value);
 437                                 status = STATUS_ERROR;
 438                                 break;
 439                         }
 440                 }
 441                 else if (strcmp(key, "format") == 0)
 442                 {
 443                         if (strcmp(value, "json") == 0)
 444                                 output_type = JSON;
 445                         else if (strcmp(value, "csv") == 0)
 446                                 output_type = CSV;
 447                         else if (strcmp(value, "tsv") == 0)
 448                                 output_type = TSV;
 449                 }
 450                 else if (strcmp(key, "points") == 0)
 451                 {
 452                         points_specified = true;
 453                         if (strcmp(value, "all") == 0)
 454                         {
 455                                 query_size = sensor->points_written;
 456                         }
 457                         else
 458                         {
 459                                 char * end;
 460                                 query_size = strtol(value, &end, 10);
 461                                 if (*end != '\0')
 462                                 {
 463                                         Log(LOGERR, "Require \"all\" or an integer value: %s = %s", key, value);
 464                                         status = STATUS_ERROR;
 465                                         break;
 466                                 }
 467                         }
 468
 469                 }
 470                 else if (strcmp(key, "start_time") == 0)
 471                 {
 472                         seek_time = true;
 473                         char * end;
 474                         start_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 (start_time < 0)
 484                         {
 485                                 start_time = current_time + start_time;
 486                         }
 487                         start_time = floor(start_time);
 488                 }
 489                 else if (strcmp(key, "end_time") == 0)
 490                 {
 491                         seek_time = true;
 492                         char * end;
 493                         end_time = strtod(value, &end);
 494                         if (*end != '\0')
 495                         {
 496                                 Log(LOGERR, "Require a double: %s = %s", key, value);
 497                                 status = STATUS_ERROR;
 498                                 break;
 499                         }
 500
 501                         // Treat negative values as being relative to the current time
 502                         if (end_time < 0)
 503                         {
 504                                 end_time = current_time + end_time;
 505                         }
 506                         end_time = ceil(end_time);
 507                 }
 508                 // For backward compatability:
 509                 else if (strcmp(key, "dump") == 0)
 510                 {
 511                         output_type = TSV;
 512                         query_size = sensor->points_written+1;
 513                 }
 514                 else
 515                 {
 516                         Log(LOGERR, "Unknown key \"%s\" (value = %s)", key, value);
 517                         status = STATUS_ERROR;
 518                         break;
 519                 }
 520         }
 521
 522         if (status != STATUS_ERROR && sensor == NULL)
 523         {
 524                 Log(LOGERR, "No valid sensor id given");
 525                 status = STATUS_ERROR;
 526         }
 527
 528         if (status == STATUS_ERROR)
 529         {
 530                 FCGI_RejectJSON(context, "Invalid input parameters");
 531                 return;
 532         }
 533
 534
 535         if (seek_time)
 536         {
 537                 if (end_time < 0 && !points_specified)
 538                         end_index = sensor->points_written;
 539                 else
 540                 {
 541                         int count = 0; DataPoint d;
 542                         end_index = FindTime(sensor, end_time, &count, &d);
 543                         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);
 544                 }
 545                 if (start_time < 0)
 546                         start_time = 0;
 547                 else
 548                 {
 549                         int count = 0; DataPoint d;
 550                         start_index = FindTime(sensor, start_time, &count, &d);
 551                         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);
 552                 }
 553
 554                 if (points_specified)
 555                         end_index = start_index + query_size;
 556         }
 557         else
 558         {
 559                 start_index = sensor->points_written - query_size;
 560
 561                 end_index = sensor->points_written;
 562         }
 563
 564         if (start_index < 0)
 565         {
 566                 Log(LOGNOTE, "start_index = %d => Clamped to 0", start_index);
 567                 start_index = 0;
 568         }
 569         if (end_index > sensor->points_written)
 570         {
 571                 Log(LOGNOTE, "end_index = %d => Clamped to %d", end_index, sensor->points_written);
 572                 end_index = sensor->points_written;
 573         }
 574
 575         switch (output_type)
 576         {
 577                 case JSON:
 578                         FCGI_BeginJSON(context, status);
 579                         FCGI_JSONLong("id", sensor->id);
 580                         FCGI_JSONKey("data");
 581                         PrintData(sensor, start_index, end_index, output_type);
 582                         FCGI_EndJSON();
 583                         break;
 584                 default:
 585                         FCGI_PrintRaw("Content-type: text/plain\r\n\r\n");
 586                         PrintData(sensor, start_index, end_index, output_type);
 587                         //Force download with content-disposition
 588                         // Sam: This is cool, but I don't think we should do it
 589                         //  - letting the user view it in the browser and then save with their own filename is more flexible
 590                         //"Content-disposition: attachment;filename=%d.csv\r\n\r\n", sensor->id);
 591                         break;
 592         }
 593
 594 }
 595
 596 /**
 597  * Setup Sensors, start Sensor polling thread(s)
 598  */
 599 void Sensor_Spawn()
 600 {
 601         // start sensor threads
 602         for (int i = 0; i < NUMSENSORS; ++i)
 603         {
 604                 Init(g_sensors+i, i);
 605                 pthread_create(&(g_sensors[i].thread), NULL, Sensor_Main, (void*)(g_sensors+i));
 606         }
 607 }
 608
 609 /**
 610  * Quit Sensor loops
 611  */
 612 void Sensor_Join()
 613 {
 614         if (!Thread_Runstate())
 615         {
 616                 Fatal("This function should not be called before Thread_QuitProgram");
 617         }
 618         for (int i = 0; i < NUMSENSORS; ++i)
 619         {
 620                 pthread_join(g_sensors[i].thread, NULL);
 621                 Destroy(g_sensors+i);
 622         }
 623 }