Merge task table and task log

src/common/Makefile

@@ -4,7 +4,7 @@ BUILD = build
 
 all: hiredis $(BUILD)/libcommon.a
 
-$(BUILD)/libcommon.a: event_loop.o common.o task.o io.o state/redis.o state/table.o state/object_table.o state/task_log.o thirdparty/ae/ae.o thirdparty/sha256.o
+$(BUILD)/libcommon.a: event_loop.o common.o task.o io.o state/redis.o state/table.o state/object_table.o state/task_table.o thirdparty/ae/ae.o thirdparty/sha256.o
 	ar rcs $@ $^
 
 $(BUILD)/common_tests: test/common_tests.c $(BUILD)/libcommon.a
@@ -16,8 +16,8 @@ $(BUILD)/db_tests: hiredis test/db_tests.c $(BUILD)/libcommon.a
 $(BUILD)/object_table_tests: hiredis test/object_table_tests.c $(BUILD)/libcommon.a
 	$(CC) -o $@ test/object_table_tests.c $(BUILD)/libcommon.a thirdparty/hiredis/libhiredis.a $(CFLAGS)
 
-$(BUILD)/task_log_tests: hiredis test/task_log_tests.c $(BUILD)/libcommon.a
-	$(CC) -o $@ test/task_log_tests.c $(BUILD)/libcommon.a thirdparty/hiredis/libhiredis.a $(CFLAGS)
+$(BUILD)/task_table_tests: hiredis test/task_table_tests.c $(BUILD)/libcommon.a
+	$(CC) -o $@ test/task_table_tests.c $(BUILD)/libcommon.a thirdparty/hiredis/libhiredis.a $(CFLAGS)
 
 $(BUILD)/io_tests: test/io_tests.c $(BUILD)/libcommon.a
 	$(CC) -o $@ $^ $(CFLAGS)
@@ -38,15 +38,15 @@ redis:
 hiredis:
 	git submodule update --init --recursive -- "thirdparty/hiredis" ; cd thirdparty/hiredis ; make
 
-test: hiredis redis $(BUILD)/common_tests $(BUILD)/task_log_tests $(BUILD)/object_table_tests $(BUILD)/db_tests $(BUILD)/io_tests $(BUILD)/task_tests $(BUILD)/redis_tests FORCE
+test: hiredis redis $(BUILD)/common_tests $(BUILD)/task_table_tests $(BUILD)/object_table_tests $(BUILD)/db_tests $(BUILD)/io_tests $(BUILD)/task_tests $(BUILD)/redis_tests FORCE
 	./thirdparty/redis-3.2.3/src/redis-server &
 	sleep 1s
 	./build/common_tests
 	./build/db_tests
 	./build/io_tests
 	./build/task_tests
 	./build/redis_tests
-	./build/task_log_tests
+	./build/task_table_tests
 	./build/object_table_tests
 
 valgrind: test
@@ -55,7 +55,7 @@ valgrind: test
 	valgrind --leak-check=full --error-exitcode=1 ./build/io_tests
 	valgrind --leak-check=full --error-exitcode=1 ./build/task_tests
 	valgrind --leak-check=full --error-exitcode=1 ./build/redis_tests
-	valgrind --leak-check=full --error-exitcode=1 ./build/task_log_tests
+	valgrind --leak-check=full --error-exitcode=1 ./build/task_table_tests
 	valgrind --leak-check=full --error-exitcode=1 ./build/object_table_tests
 
 FORCE:

src/common/common.c

@@ -25,7 +25,11 @@ unique_id globally_unique_id(void) {
 }
 
 bool object_ids_equal(object_id first_id, object_id second_id) {
-  return memcmp(&first_id, &second_id, sizeof(object_id)) == 0 ? true : false;
+  return UNIQUE_ID_EQ(first_id, second_id);
+}
+
+bool object_id_is_nil(object_id id) {
+  return object_ids_equal(id, NIL_OBJECT_ID);
 }
 
 char *sha1_to_hex(const unsigned char *sha1, char *buffer) {

src/common/common.h

@@ -56,6 +56,10 @@
 
 #define UNIQUE_ID_SIZE 20
 
+#define UNIQUE_ID_EQ(id1, id2) (memcmp((id1).id, (id2).id, UNIQUE_ID_SIZE) == 0)
+
+#define IS_NIL_ID(id) UNIQUE_ID_EQ(id, NIL_ID)
+
 typedef struct { unsigned char id[UNIQUE_ID_SIZE]; } unique_id;
 
 extern const UT_icd object_id_icd;
@@ -70,6 +74,8 @@ unique_id globally_unique_id(void);
  * UNIQUE_ID_SIZE + 1 */
 char *sha1_to_hex(const unsigned char *sha1, char *buffer);
 
+#define NIL_OBJECT_ID NIL_ID
+
 typedef unique_id object_id;
 
 /**
@@ -81,4 +87,12 @@ typedef unique_id object_id;
  */
 bool object_ids_equal(object_id first_id, object_id second_id);
 
+/**
+ * Compare a object ID to the nil ID.
+ *
+ * @param id The object ID to compare to nil.
+ * @return True if the object ID is equal to nil.
+ */
+bool object_id_is_nil(object_id id);
+
 #endif

src/common/doc/tasks.md

@@ -3,6 +3,7 @@
 A *task specification* contains all information that is needed for computing
 the results of a task:
 
+- The ID of the task
 - The function ID of the function that executes the task
 - The arguments (either object IDs for pass by reference
 or values for pass by value)
@@ -11,23 +12,21 @@ or values for pass by value)
 From these, a task ID can be computed which is also stored in the task
 specification.
 
-A *task instance* represents one execution of a task specification.
+A *task* represents the execution of a task specification.
 It consists of:
 
 - A scheduling state (WAITING, SCHEDULED, RUNNING, DONE)
 - The target node where the task is scheduled or executed
-- A unique task instance ID that identifies the particular execution
-  of the task.
+- The task specification
 
 The task data structures are defined in `common/task.h`.
 
-The *task log* is a mapping from the task instance ID to a sequence of
-updates to the status of the task instance. It is updated by various parts
-of the system:
+The *task table* is a mapping from the task ID to the *task* information. It is
+updated by various parts of the system:
 
 1. The local scheduler writes it with status WAITING when submits a task to the global scheduler
 2. The global scheduler appends an update WAITING -> SCHEDULED together with the node ID when assigning the task to a local scheduler
 3. The local scheduler appends an update SCHEDULED -> RUNNING when it assigns a task to a worker
 4. The local scheduler appends an update RUNNING -> DONE when the task finishes execution
 
-The task log is defined in `common/state/task_log.h`.
+The task table is defined in `common/state/task_table.h`.

src/common/lib/python/common_extension.c

@@ -176,7 +176,7 @@ static PyObject *PyTask_function_id(PyObject *self) {
 }
 
 static PyObject *PyTask_task_id(PyObject *self) {
-  task_id task_id = task_task_id(((PyTask *) self)->spec);
+  task_id task_id = task_spec_id(((PyTask *) self)->spec);
   return PyObjectID_make(task_id);
 }
 

src/common/state/object_table.c

@@ -36,3 +36,24 @@ void object_table_subscribe(
   init_table_callback(db_handle, object_id, sub_data, retry, done_callback,
                       redis_object_table_subscribe, user_context);
 }
+
+void result_table_add(db_handle *db_handle,
+                      object_id object_id,
+                      task_id task_id_arg,
+                      retry_info *retry,
+                      result_table_done_callback done_callback,
+                      void *user_context) {
+  task_id *task_id_copy = malloc(UNIQUE_ID_SIZE);
+  memcpy(task_id_copy, task_id_arg.id, UNIQUE_ID_SIZE);
+  init_table_callback(db_handle, object_id, task_id_copy, retry, done_callback,
+                      redis_result_table_add, user_context);
+}
+
+void result_table_lookup(db_handle *db_handle,
+                         object_id object_id,
+                         retry_info *retry,
+                         result_table_lookup_callback done_callback,
+                         void *user_context) {
+  init_table_callback(db_handle, object_id, NULL, retry, done_callback,
+                      redis_result_table_lookup, user_context);
+}

src/common/state/object_table.h

@@ -4,6 +4,7 @@
 #include "common.h"
 #include "table.h"
 #include "db.h"
+#include "task.h"
 
 /*
  *  ==== Lookup call and callback ====
@@ -123,4 +124,55 @@ typedef struct {
   void *subscribe_context;
 } object_table_subscribe_data;
 
+/*
+ *  ==== Result table ====
+ */
+
+/**
+ * Callback called when the add/remove operation for a result table entry
+ * completes. */
+typedef void (*result_table_done_callback)(object_id object_id,
+                                           void *user_context);
+
+/**
+ * Add information about a new object to the object table. This
+ * is immutable information like the ID of the task that
+ * created the object.
+ *
+ * @param db_handle Handle to object_table database.
+ * @param object_id ID of the object to add.
+ * @param task_id ID of the task that creates this object.
+ * @param retry Information about retrying the request to the database.
+ * @param done_callback Function to be called when database returns result.
+ * @param user_context Context passed by the caller.
+ * @return Void.
+ */
+void result_table_add(db_handle *db_handle,
+                      object_id object_id,
+                      task_id task_id,
+                      retry_info *retry,
+                      result_table_done_callback done_callback,
+                      void *user_context);
+
+/** Callback called when the result table lookup completes. */
+typedef void (*result_table_lookup_callback)(object_id object_id,
+                                             task *task,
+                                             void *user_context);
+
+/**
+ * Lookup the task that created an object in the result table.
+ *
+ * @param db_handle Handle to object_table database.
+ * @param object_id ID of the object to lookup.
+ * @param retry Information about retrying the request to the database.
+ * @param done_callback Function to be called when database returns result.
+ * @param user_context Context passed by the caller.
+ * @return Void.
+ */
+void result_table_lookup(db_handle *db_handle,
+                         object_id object_id,
+                         retry_info *retry,
+                         result_table_lookup_callback done_callback,
+                         void *user_context);
+
 #endif /* OBJECT_TABLE_H */