Update the task table (#129)

* Update the task table

* Move updating task table out of scheduling algorithm.

src/photon/photon.h

@@ -31,6 +31,8 @@ enum photon_message_type {
 /** Contains all information that is associated to a worker. */
 typedef struct {
   int sock;
+  /** A pointer to a task object, to update the task table. */
+  task *task_in_progress;
 } worker;
 // clang-format on
 

src/photon/photon_algorithm.c

@@ -215,6 +215,12 @@ void queue_task_locally(local_scheduler_state *state,
   memcpy(elt->spec, spec, task_spec_size(spec));
   elt->from_global_scheduler = from_global_scheduler;
   DL_APPEND(algorithm_state->task_queue, elt);
+  if (!from_global_scheduler && state->db != NULL) {
+    task *task =
+        alloc_task(spec, TASK_STATUS_SCHEDULED, get_db_client_id(state->db));
+    task_table_add_task(state->db, task, (retry_info *) &photon_retry, NULL,
+                        NULL);
+  }
 }
 
 void give_task_to_global_scheduler(local_scheduler_state *state,
@@ -282,6 +288,10 @@ void handle_task_scheduled(local_scheduler_state *state,
 void handle_worker_available(local_scheduler_state *state,
                              scheduling_algorithm_state *algorithm_state,
                              int worker_index) {
+  worker *available_worker =
+      (worker *) utarray_eltptr(state->workers, worker_index);
+  CHECK(available_worker->task_in_progress == NULL);
+  /* Try to schedule another task to the worker. */
   int scheduled_task =
       find_and_schedule_task_if_possible(state, algorithm_state, worker_index);
   /* If we couldn't find a task to schedule, add the worker to the queue of

src/photon/photon_scheduler.c

@@ -89,18 +89,14 @@ void assign_task_to_worker(local_scheduler_state *state,
   write_message(w->sock, EXECUTE_TASK, task_spec_size(spec), (uint8_t *) spec);
   /* Update the global task table. */
   if (state->db != NULL) {
-    retry_info retry;
-    memset(&retry, 0, sizeof(retry));
-    retry.num_retries = 0;
-    retry.timeout = 100;
-    retry.fail_callback = NULL;
     task *task =
         alloc_task(spec, TASK_STATUS_RUNNING, get_db_client_id(state->db));
-    if (from_global_scheduler) {
-      task_table_update(state->db, task, (retry_info *) &retry, NULL, NULL);
-    } else {
-      task_table_add_task(state->db, task, (retry_info *) &retry, NULL, NULL);
-    }
+    task_table_update(state->db, task, (retry_info *) &photon_retry, NULL,
+                      NULL);
+    /* Record which task this worker is executing. This will be freed in
+     * process_message when the worker sends a GET_TASK message to the local
+     * scheduler. */
+    w->task_in_progress = copy_task(task);
   }
 }
 
@@ -142,11 +138,11 @@ void reconstruct_object_task_lookup_callback(object_id reconstruct_object_id,
    * reconstruction operation. NOTE: This codepath is not responsible for
    * detecting failure of the other reconstruction, or updating the
    * scheduling_state accordingly. */
-  /* TODO(swang): Once we add code to modify the task table properly, this
-   * should also include TASK_STATUS_RUNNING. */
   scheduling_state task_status = task_state(task);
   if (task_status == TASK_STATUS_WAITING ||
-      task_status == TASK_STATUS_SCHEDULED) {
+      task_status == TASK_STATUS_SCHEDULED ||
+      task_status == TASK_STATUS_RUNNING) {
+    LOG_DEBUG("Task to reconstruct had scheduling state %d", task_status);
     return;
   }
   /* Recursively reconstruct the task's inputs, if necessary. */
@@ -207,6 +203,19 @@ void process_message(event_loop *loop,
   case GET_TASK: {
     worker_index *wi;
     HASH_FIND_INT(state->worker_index, &client_sock, wi);
+    /* Update the task table with the completed task. */
+    worker *available_worker =
+        (worker *) utarray_eltptr(state->workers, wi->worker_index);
+    if (state->db != NULL && available_worker->task_in_progress != NULL) {
+      task_set_state(available_worker->task_in_progress, TASK_STATUS_DONE);
+      task_table_update(state->db, available_worker->task_in_progress,
+                        (retry_info *) &photon_retry, NULL, NULL);
+      /* The call to task_table_update takes ownership of the task_in_progress,
+       * so we set the pointer to NULL so it is not used. */
+      available_worker->task_in_progress = NULL;
+    }
+    /* Let the scheduling algorithm process the fact that there is an available
+     * worker. */
     handle_worker_available(state, state->algorithm_state, wi->worker_index);
   } break;
   case RECONSTRUCT_OBJECT: {