/* Interaction with cloud storage. We expose very simple GET/PUT style
* interface, which different backends can implement. Available backends
- * (will) include Amazon S3 and a simple local store for testing purposes. */
+ * (will) include Amazon S3 and a simple local store for testing purposes.
+ * Operations may be performed asynchronously. */
struct _BlueSkyStore {
const BlueSkyStoreImplementation *impl;
gpointer handle;
+
+ GMutex *lock;
+ GCond *cond_idle;
+ int pending; /* Count of operations not yet complete. */
};
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)
{
BlueSkyStore *store = g_new(BlueSkyStore, 1);
store->impl = impl;
store->handle = handle;
+ store->lock = g_mutex_new();
+ store->cond_idle = g_cond_new();
+ store->pending = 0;
return store;
}
g_free(store);
}
-BlueSkyRCStr *bluesky_store_get(BlueSkyStore *store, const gchar *key)
+BlueSkyStoreAsync *bluesky_store_async_new(BlueSkyStore *store)
{
- return store->impl->get(store->handle, key);
+ BlueSkyStoreAsync *async;
+
+ async = g_new(BlueSkyStoreAsync, 1);
+ async->store = store;
+ async->lock = g_mutex_new();
+ async->completion_cond = g_cond_new();
+ async->refcount = 1;
+ async->status = ASYNC_NEW;
+ async->op = STORE_OP_NONE;
+ async->key = NULL;
+ async->data = NULL;
+ async->result = -1;
+ async->notifiers = NULL;
+ async->store_private = NULL;
+
+ return async;
}
-void bluesky_store_put(BlueSkyStore *store,
- const gchar *key, BlueSkyRCStr *val)
+void bluesky_store_async_ref(BlueSkyStoreAsync *async)
{
- store->impl->put(store->handle, key, val);
+ if (async == NULL)
+ return;
+
+ g_return_if_fail(g_atomic_int_get(&async->refcount) > 0);
+
+ g_atomic_int_inc(&async->refcount);
}
-/* Create and return a new reference-counted string. The reference count is
- * initially one. The newly-returned string takes ownership of the memory
- * pointed at by data, and will call g_free on it when the reference count
- * drops to zero. */
-BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len)
+void bluesky_store_async_unref(BlueSkyStoreAsync *async)
{
- BlueSkyRCStr *string = g_new(BlueSkyRCStr, 1);
- string->data = data;
- string->len = len;
- g_atomic_int_set(&string->refcount, 1);
- return string;
+ if (async == NULL)
+ return;
+
+ if (g_atomic_int_dec_and_test(&async->refcount)) {
+ async->store->impl->cleanup(async->store->handle, async);
+ g_mutex_free(async->lock);
+ g_cond_free(async->completion_cond);
+ g_free(async->key);
+ bluesky_string_unref(async->data);
+ g_free(async);
+ }
}
-void bluesky_string_ref(BlueSkyRCStr *string)
+/* Block until the given operation has completed. */
+void bluesky_store_async_wait(BlueSkyStoreAsync *async)
{
- if (string == NULL)
+ g_return_if_fail(async != NULL);
+ g_mutex_lock(async->lock);
+
+ if (async->status == ASYNC_NEW) {
+ g_error("bluesky_store_async_wait on a new async object!\n");
+ g_mutex_unlock(async->lock);
return;
+ }
+
+ while (async->status != ASYNC_COMPLETE) {
+ g_cond_wait(async->completion_cond, async->lock);
+ }
- g_atomic_int_inc(&string->refcount);
+ g_mutex_unlock(async->lock);
}
-void bluesky_string_unref(BlueSkyRCStr *string)
+/* Add a notifier function to be called when the operation completes. */
+void bluesky_store_async_add_notifier(BlueSkyStoreAsync *async,
+ GFunc func, gpointer user_data)
{
- if (string == NULL)
+ 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 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)
+{
+ 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);
+ }
+}
+
+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_log("bluesky/store", G_LOG_LEVEL_DEBUG, "submit: %s %s",
+ async->op == STORE_OP_GET ? "GET"
+ : async->op == STORE_OP_PUT ? "PUT"
+ : async->op == STORE_OP_DELETE ? "DELETE" : "???",
+ async->key);
- if (g_atomic_int_dec_and_test(&string->refcount)) {
- g_free(string->data);
- g_free(string);
+ g_mutex_lock(async->store->lock);
+ async->store->pending++;
+ g_mutex_unlock(async->store->lock);
+
+ 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 *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);
}
-/* Duplicate and return a new reference-counted string, containing a copy of
- * the original data, with a reference count of 1. As an optimization, if the
- * passed-in string already has a reference count of 1, the original is
- * returned. Can be used to make a mutable copy of a shared string. For this
- * to truly be safe, it is probably needed that there be some type of lock
- * protecting access to the string. */
-BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string)
+/* 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)
{
- if (string == NULL)
- return NULL;
+ 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, barrier);
+}
- if (g_atomic_int_dec_and_test(&string->refcount)) {
- /* There are no other shared copies, so return this one. */
- g_atomic_int_inc(&string->refcount);
- return string;
- } else {
- return bluesky_string_new(g_memdup(string->data, string->len),
- string->len);
+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);
+ g_print("Waiting for pending store operations to complete...\n");
+ while (store->pending > 0) {
+ g_cond_wait(store->cond_idle, store->lock);
}
+ g_mutex_unlock(store->lock);
+ g_print("Operations are complete.\n");
+}
+
+/* Convenience wrappers that perform a single operation synchronously. */
+BlueSkyRCStr *bluesky_store_get(BlueSkyStore *store, const gchar *key)
+{
+ BlueSkyStoreAsync *async = bluesky_store_async_new(store);
+ async->op = STORE_OP_GET;
+ async->key = g_strdup(key);
+ bluesky_store_async_submit(async);
+
+ bluesky_store_async_wait(async);
+
+ BlueSkyRCStr *data = async->data;
+ bluesky_string_ref(data);
+ bluesky_store_async_unref(async);
+ return data;
+}
+
+void bluesky_store_put(BlueSkyStore *store,
+ const gchar *key, BlueSkyRCStr *val)
+{
+ BlueSkyStoreAsync *async = bluesky_store_async_new(store);
+ async->op = STORE_OP_PUT;
+ async->key = g_strdup(key);
+ bluesky_string_ref(val);
+ async->data = val;
+ bluesky_store_async_submit(async);
+
+ bluesky_store_async_wait(async);
+ bluesky_store_async_unref(async);
}
/* Simple in-memory data store for test purposes. */
g_hash_table_insert(store->store, g_strdup(key), val);
}
+static void memstore_submit(gpointer s, BlueSkyStoreAsync *async)
+{
+ g_return_if_fail(async->status == ASYNC_NEW);
+ g_return_if_fail(async->op != STORE_OP_NONE);
+
+ switch (async->op) {
+ case STORE_OP_GET:
+ async->data = memstore_get(s, async->key);
+ break;
+
+ case STORE_OP_PUT:
+ memstore_put(s, async->key, async->data);
+ break;
+
+ default:
+ g_warning("Uknown operation type for MemStore: %d\n", async->op);
+ return;
+ }
+
+ bluesky_store_async_mark_complete(async);
+}
+
+static void memstore_cleanup(gpointer store, BlueSkyStoreAsync *async)
+{
+}
+
static BlueSkyStoreImplementation memstore_impl = {
.create = memstore_create,
.destroy = memstore_destroy,
- .get = memstore_get,
- .put = memstore_put,
+ .submit = memstore_submit,
+ .cleanup = memstore_cleanup,
};
/* Store implementation which writes data as files to disk. */
{
}
-static BlueSkyRCStr *filestore_get(gpointer s, const gchar *key)
+static BlueSkyRCStr *filestore_get(const gchar *key)
{
gchar *contents = NULL;
gsize length;
return bluesky_string_new(contents, length);
}
-static void filestore_put(gpointer s, const gchar *key, BlueSkyRCStr *val)
+static void filestore_put(const gchar *key, BlueSkyRCStr *val)
{
g_file_set_contents(key, val->data, val->len, NULL);
}
+static void filestore_submit(gpointer s, BlueSkyStoreAsync *async)
+{
+ g_return_if_fail(async->status == ASYNC_NEW);
+ g_return_if_fail(async->op != STORE_OP_NONE);
+
+ switch (async->op) {
+ case STORE_OP_GET:
+ async->data = filestore_get(async->key);
+ break;
+
+ case STORE_OP_PUT:
+ filestore_put(async->key, async->data);
+ break;
+
+ default:
+ g_warning("Uknown operation type for FileStore: %d\n", async->op);
+ return;
+ }
+
+ bluesky_store_async_mark_complete(async);
+}
+
+static void filestore_cleanup(gpointer store, BlueSkyStoreAsync *async)
+{
+}
+
static BlueSkyStoreImplementation filestore_impl = {
.create = filestore_create,
.destroy = filestore_destroy,
- .get = filestore_get,
- .put = filestore_put,
+ .submit = filestore_submit,
+ .cleanup = filestore_cleanup,
};
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");
}