Fix SensorHandler while loop

[matches/MCTX3420.git] / server / sensor.c

diff --git a/server/sensor.c b/server/sensor.c
index e69de29..ab687af 100644 (file)
--- a/server/sensor.c
+++ b/server/sensor.c
@@ -0,0 +1,150 @@
+/**
+ * @file sensor.c
+ * @purpose Implementation of sensor thread
+ * TODO: Finalise implementation
+ */
+
+
+
+#include "sensor.h"
+#include "log.h"
+#include <math.h>
+
+/**
+ * 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
+ */
+DataPoint GetData(int sensor_id)
+{
+       // 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++;
+       switch (sensor_id)
+       {
+               case SENSOR_TEST0:
+                       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 Sensor_Init(Sensor * s, int id)
+{
+       s->write_index = 0;
+       s->read_offset = 0;
+       s->id = id;
+
+       #define FILENAMESIZE BUFSIZ
+       char filename[FILENAMESIZE];
+       //if (s->id >= pow(10, FILENAMESIZE))
+       if (false)
+       {
+               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 (true) //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)
+               {
+                       s->buffer[s->write_index] = GetData(s->id);
+                       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));
+                       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
+               
+       }
+       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;
+}
+
+