+/* Blue Sky: File Systems in the Cloud
+ *
+ * Copyright (C) 2009 The Regents of the University of California
+ * Written by Michael Vrable <mvrable@cs.ucsd.edu>
+ *
+ * TODO: Licensing
+ */
+
+#include <stdint.h>
+#include <glib.h>
+#include <string.h>
+
+#include "bluesky.h"
+
+/* 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. */
+
+/* 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)
+{
+ BlueSkyRCStr *string = g_new(BlueSkyRCStr, 1);
+ string->data = data;
+ string->len = len;
+ g_atomic_int_set(&string->refcount, 1);
+ return string;
+}
+
+void bluesky_string_ref(BlueSkyRCStr *string)
+{
+ g_atomic_int_inc(&string->refcount);
+}
+
+void bluesky_string_unref(BlueSkyRCStr *string)
+{
+ if (g_atomic_int_dec_and_test(&string->refcount)) {
+ g_free(string->data);
+ g_free(string);
+ }
+}
+
+/* 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. */
+BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string)
+{
+ 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);
+ }
+}
+
+/* Simple in-memory data store for test purposes. */
+typedef struct {
+ GMutex *lock;
+
+ /* TODO: A hashtable isn't optimal for list queries... */
+ GHashTable *store;
+} MemStore;
+
+MemStore *memstore_new()
+{
+ MemStore *store = g_new(MemStore, 1);
+ store->lock = g_mutex_new();
+ store->store = g_hash_table_new_full(g_str_hash, g_str_equal,
+ g_free,
+ (GDestroyNotify)bluesky_string_unref);
+
+ return store;
+}
+
+BlueSkyRCStr *memstore_get(MemStore *store, const gchar *key)
+{
+ BlueSkyRCStr *s = g_hash_table_lookup(store->store, key);
+ if (s != NULL)
+ bluesky_string_ref(s);
+ return s;
+}
+
+void memstore_put(MemStore *store, const gchar *key, BlueSkyRCStr *val)
+{
+ bluesky_string_ref(val);
+ g_hash_table_insert(store->store, g_strdup(key), val);
+}