[SERVER] Create skeleton of upcoming watchdog/job executor

2 files changed, 107 insertions, 0 deletions

diff --git a/src/server/job.c b/src/server/job.c
new file mode 100644
index 0000000..8753c2c
--- /dev/null
+++ b/src/server/job.c
@@ -0,0 +1,101 @@
+#include "job.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+
+#define DEV_STRLEN 12 // INCLUDING NULLCHAR (increase to 13 if you need more than 100 (0-99) devices)
+#define MAX_NUM_DEVICES_TO_CHECK 100
+
+#ifndef	FALSE
+#define	FALSE	(0)
+#endif
+
+#ifndef	TRUE
+#define	TRUE	(!FALSE)
+#endif
+
+typedef struct
+{
+	char available;
+	char name[DEV_STRLEN];
+} device_t;
+
+// "/dev/dnbdXX" == 11 bytes per device + nullchar = 12
+static device_t *devices = NULL;
+static int num_devices = 0;
+
+static char keep_running = TRUE;
+
+static char* get_free_device();
+
+void* dnbd3_job_thread(void *data)
+{
+	int i, j;
+	// Determine number of available dnbd3 devices, which are needed for proxy mode
+	char dev[DEV_STRLEN];
+	for (i = 0; i < MAX_NUM_DEVICES_TO_CHECK; ++i)
+	{
+		sprintf(dev, "/dev/dnbd%d", i);
+		if (access(dev, W_OK | R_OK)) // Need RW access to device to read and do ioctl
+			continue;
+		++num_devices;
+	}
+	if (num_devices > 0)
+	{
+		devices = calloc(num_devices, sizeof(*devices));
+		for (i = 0, j = 0; i < MAX_NUM_DEVICES_TO_CHECK; ++i)
+		{
+			memset(dev, 0, DEV_STRLEN);
+			sprintf(dev, "/dev/dnbd%d", i);
+			if (access(dev, W_OK | R_OK))
+				continue;
+			if (j >= num_devices) // More available devices during second iteration? :-(
+				break;
+			memcpy(devices[j].name, dev, DEV_STRLEN);
+			devices[j].available = TRUE;
+			++j;
+		}
+	}
+	//
+	// Job/Watchdog mainloop
+	while (keep_running)
+	{
+		// TODO: Update image atime
+		// TODO: Handle image deletion
+		// TODO: Replicate proxied images (limited bandwidth)
+		// TODO: Query other servers for new images/status/...
+		// TODO: Switch server of dnbd device based on more sophisticated inputs than just rtt
+	}
+	//
+	free(devices);
+	devices = NULL;
+	pthread_exit(NULL);
+	return NULL;
+}
+
+void dnbd3_job_shutdown()
+{
+	keep_running = FALSE;
+}
+
+/**
+ * Get full name of an available dnbd3 device, eg. /dev/dnbd4
+ * Returned buffer is owned by this module, do not modify or free!
+ */
+static char* get_free_device()
+{
+	if (devices == NULL)
+		return NULL;
+	int i;
+	for (i = 0; i < num_devices; ++i)
+	{
+		if (!devices[i].available)
+			continue;
+		// TODO: Check sysfs if device is maybe already connected
+		return devices[i].name;
+	}
+	return NULL;
+}
diff --git a/src/server/job.h b/src/server/job.h
new file mode 100644
index 0000000..87be5d5
--- /dev/null
+++ b/src/server/job.h
@@ -0,0 +1,6 @@
+#ifndef JOB_H_
+#define JOB_H_
+
+void* dnbd3_job_thread(void *data);
+
+#endif