Work on a storage barrier operation.

The barrier completes when all of a set of operations has completed.

diff --git a/bluesky/bluesky-private.h b/bluesky/bluesky-private.h
index 9ca0658..d00f7c3 100644 (file)
--- a/bluesky/bluesky-private.h
+++ b/bluesky/bluesky-private.h
@@ -36,6 +36,7 @@ typedef enum {
     STORE_OP_GET,
     STORE_OP_PUT,
     STORE_OP_DELETE,
+    STORE_OP_BARRIER,       // Waits for other selected operations to complete
 } BlueSkyStoreOp;
 
 typedef enum {
@@ -45,6 +46,7 @@ typedef enum {
     ASYNC_COMPLETE,         // Operation finished, results available
 } BlueSkyAsyncStatus;
 
+struct BlueSkyNotifierList;
 typedef struct {
     BlueSkyStore *store;
 
@@ -60,10 +62,22 @@ typedef struct {
     BlueSkyRCStr *data;         /* Data read/to write */
 
     int result;                 /* Result code; 0 for success. */
+    struct BlueSkyNotifierList *notifiers;
 
     gpointer store_private;     /* For use by the storage implementation */
 } BlueSkyStoreAsync;
 
+/* Support for notification lists.  These are lists of one-shot functions which
+ * can be called when certain events--primarily, competed storage
+ * events--occur.  Multiple notifiers can be added, but no particular order is
+ * guaranteed for the notification functions to be called. */
+struct BlueSkyNotifierList {
+    struct BlueSkyNotifierList *next;
+    GFunc func;
+    BlueSkyStoreAsync *async;
+    gpointer user_data;     // Passed to the function when called
+};
+
 /* The abstraction layer for storage, allowing multiple implementations. */
 typedef struct {
     /* Create a new store instance and return a handle to it. */
@@ -87,10 +101,15 @@ BlueSkyStoreAsync *bluesky_store_async_new(BlueSkyStore *store);
 void bluesky_store_async_ref(BlueSkyStoreAsync *async);
 void bluesky_store_async_unref(BlueSkyStoreAsync *async);
 void bluesky_store_async_wait(BlueSkyStoreAsync *async);
+void bluesky_store_async_add_notifier(BlueSkyStoreAsync *async,
+                                      GFunc func, gpointer user_data);
 void bluesky_store_async_mark_complete(BlueSkyStoreAsync *async);
 void bluesky_store_async_submit(BlueSkyStoreAsync *async);
 void bluesky_store_sync(BlueSkyStore *store);
 
+void bluesky_store_add_barrier(BlueSkyStoreAsync *barrier,
+                               BlueSkyStoreAsync *async);
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/bluesky/file.c b/bluesky/file.c
index 9f4d980..f7e8fca 100644 (file)
--- a/bluesky/file.c
+++ b/bluesky/file.c
@@ -182,6 +182,11 @@ void bluesky_block_fetch(BlueSkyFS *fs, BlueSkyBlock *block)
     block->type = BLUESKY_BLOCK_CACHED;
 }
 
+static void finished(gpointer a, gpointer b)
+{
+    g_print("Barrier completed!\n");
+}
+
 /* Write the given block to cloud-backed storage and mark it clean. */
 void bluesky_block_flush(BlueSkyFS *fs, BlueSkyBlock *block)
 {
@@ -207,6 +212,13 @@ void bluesky_block_flush(BlueSkyFS *fs, BlueSkyBlock *block)
     g_free(block->ref);
     block->ref = name;
 
+    BlueSkyStoreAsync *barrier = bluesky_store_async_new(fs->store);
+    barrier->op = STORE_OP_BARRIER;
+    bluesky_store_add_barrier(barrier, async);
+    bluesky_store_async_add_notifier(barrier, finished, NULL);
+    bluesky_store_async_submit(barrier);
+    bluesky_store_async_unref(barrier);
+
     /* block->type = BLUESKY_BLOCK_CACHED; */
     bluesky_string_unref(block->data);
     block->data = NULL;

diff --git a/bluesky/store.c b/bluesky/store.c
index 7c8123c..cc8a5e4 100644 (file)
--- a/bluesky/store.c
+++ b/bluesky/store.c
@@ -28,6 +28,13 @@ struct _BlueSkyStore {
 
 GHashTable *store_implementations;
 
+/* Thread pool for calling notifier functions when an operation completes.
+ * These are called in a separate thread for locking reasons: we want to call
+ * the notifiers without the lock on the async object held, but completion
+ * occurs when the lock is held--so we need some way to defer the call.  This
+ * isn't really optimal from a cache-locality standpoint. */
+static GThreadPool *notifier_thread_pool;
+
 void bluesky_store_register(const BlueSkyStoreImplementation *impl,
                             const gchar *name)
 {
@@ -75,6 +82,7 @@ BlueSkyStoreAsync *bluesky_store_async_new(BlueSkyStore *store)
     async->key = NULL;
     async->data = NULL;
     async->result = -1;
+    async->notifiers = NULL;
     async->store_private = NULL;
 
     return async;
@@ -85,6 +93,8 @@ void bluesky_store_async_ref(BlueSkyStoreAsync *async)
     if (async == NULL)
         return;
 
+    g_return_if_fail(g_atomic_int_get(&async->refcount) > 0);
+
     g_atomic_int_inc(&async->refcount);
 }
 
@@ -123,37 +133,110 @@ void bluesky_store_async_wait(BlueSkyStoreAsync *async)
     g_mutex_unlock(async->lock);
 }
 
+/* Add a notifier function to be called when the operation completes. */
+void bluesky_store_async_add_notifier(BlueSkyStoreAsync *async,
+                                      GFunc func, gpointer user_data)
+{
+    struct BlueSkyNotifierList *nl = g_new(struct BlueSkyNotifierList, 1);
+    nl->next = async->notifiers;
+    nl->func = func;
+    nl->async = async; bluesky_store_async_ref(async);
+    nl->user_data = user_data;
+    if (async->status == ASYNC_COMPLETE) {
+        g_thread_pool_push(notifier_thread_pool, nl, NULL);
+    } else {
+        async->notifiers = nl;
+    }
+}
+
 /* Mark an asynchronous operation as complete.  This should only be called by
- * the store implementations.  The lock must be held when calling this
- * function. */
+ * the store implementations.  The lock should be held when calling this
+ * function.  Any notifier functions will be called, but in a separate thread
+ * and without the lock held. */
 void bluesky_store_async_mark_complete(BlueSkyStoreAsync *async)
 {
-    if (async->status != ASYNC_COMPLETE) {
-        g_mutex_lock(async->store->lock);
-        async->store->pending--;
-        if (async->store->pending == 0)
-            g_cond_broadcast(async->store->cond_idle);
-        g_mutex_unlock(async->store->lock);
-    }
+    g_return_if_fail(async->status != ASYNC_COMPLETE);
+
+    g_mutex_lock(async->store->lock);
+    async->store->pending--;
+    if (async->store->pending == 0)
+        g_cond_broadcast(async->store->cond_idle);
+    g_mutex_unlock(async->store->lock);
 
     async->status = ASYNC_COMPLETE;
     g_cond_broadcast(async->completion_cond);
+
+    while (async->notifiers != NULL) {
+        struct BlueSkyNotifierList *nl = async->notifiers;
+        async->notifiers = nl->next;
+        g_thread_pool_push(notifier_thread_pool, nl, NULL);
+    }
+}
+
+static void test_notifier(gpointer a, gpointer u)
+{
+    g_print("Notifier called!\n");
 }
 
 void bluesky_store_async_submit(BlueSkyStoreAsync *async)
 {
     BlueSkyStore *store = async->store;
 
+    /* Barriers are handled specially, and not handed down the storage
+     * implementation layer. */
+    if (async->op = STORE_OP_BARRIER) {
+        async->status = ASYNC_RUNNING;
+        if (GPOINTER_TO_INT(async->store_private) == 0)
+            bluesky_store_async_mark_complete(async);
+        return;
+    }
+
     g_mutex_lock(async->store->lock);
     async->store->pending++;
     g_mutex_unlock(async->store->lock);
 
+    bluesky_store_async_add_notifier(async, test_notifier, NULL);
     store->impl->submit(store->handle, async);
 
     if (bluesky_options.synchronous_stores)
         bluesky_store_async_wait(async);
 }
 
+static void op_complete(gpointer a, gpointer b)
+{
+    BlueSkyStoreAsync *async = (BlueSkyStoreAsync *)a;
+    BlueSkyStoreAsync *barrier = (BlueSkyStoreAsync *)b;
+
+    g_mutex_lock(barrier->lock);
+    barrier->store_private
+        = GINT_TO_POINTER(GPOINTER_TO_INT(barrier->store_private) - 1);
+    if (GPOINTER_TO_INT(barrier->store_private) == 0
+            && barrier->status != ASYNC_NEW) {
+        bluesky_store_async_mark_complete(barrier);
+    }
+    g_mutex_unlock(barrier->lock);
+}
+
+/* Add the given operation to the barrier.  The barrier will not complete until
+ * all operations added to it have completed. */
+void bluesky_store_add_barrier(BlueSkyStoreAsync *barrier,
+                               BlueSkyStoreAsync *async)
+{
+    g_return_if_fail(barrier->op == STORE_OP_BARRIER);
+    barrier->store_private
+        = GINT_TO_POINTER(GPOINTER_TO_INT(barrier->store_private) + 1);
+    bluesky_store_async_add_notifier(async, op_complete, NULL);
+}
+
+static void notifier_task(gpointer n, gpointer s)
+{
+    struct BlueSkyNotifierList *notifier = (struct BlueSkyNotifierList *)n;
+
+    notifier->func(notifier->async, notifier->user_data);
+    bluesky_store_async_unref(notifier->async);
+    g_free(notifier);
+}
+
 void bluesky_store_sync(BlueSkyStore *store)
 {
     g_mutex_lock(store->lock);
@@ -282,6 +365,8 @@ static BlueSkyStoreImplementation filestore_impl = {
 void bluesky_store_init()
 {
     store_implementations = g_hash_table_new(g_str_hash, g_str_equal);
+    notifier_thread_pool = g_thread_pool_new(notifier_task, NULL, -1, FALSE,
+                                             NULL);
     //bluesky_store_register(&memstore_impl, "mem");
     //bluesky_store_register(&filestore_impl, "file");
 }