1 /* Blue Sky: File Systems in the Cloud
3 * Copyright (C) 2009 The Regents of the University of California
4 * Written by Michael Vrable <mvrable@cs.ucsd.edu>
14 #include "bluesky-private.h"
16 /* The locations hash table in the file system is used to map objects to their locations. Objects are named using 128- */
21 BlueSkyCloudPointer *cloud_loc;
22 } BlueSkyLocationEntry;
24 BlueSkyCloudID bluesky_cloudlog_new_id()
27 bluesky_crypt_random_bytes((uint8_t *)&id.bytes, sizeof(id));
31 gchar *bluesky_cloudlog_id_to_string(BlueSkyCloudID id)
33 char buf[sizeof(BlueSkyCloudID) * 2 + 1];
36 for (int i = 0; i < sizeof(BlueSkyCloudID); i++) {
37 sprintf(&buf[2*i], "%02x", (uint8_t)(id.bytes[i]));
43 BlueSkyCloudID bluesky_cloudlog_id_from_string(const gchar *idstr)
46 memset(&id, 0, sizeof(id));
47 for (int i = 0; i < 2*sizeof(BlueSkyCloudID); i++) {
50 g_warning("Short cloud id: %s\n", idstr);
54 if (c >= '0' && c <= '9')
56 else if (c >= 'a' && c <= 'f')
59 g_warning("Bad character in cloud id: %s\n", idstr);
60 id.bytes[i / 2] += val << (i % 2 ? 0 : 4);
65 gboolean bluesky_cloudlog_equal(gconstpointer a, gconstpointer b)
67 BlueSkyCloudID *id1 = (BlueSkyCloudID *)a, *id2 = (BlueSkyCloudID *)b;
69 return memcmp(id1, id2, sizeof(BlueSkyCloudID)) == 0;
72 guint bluesky_cloudlog_hash(gconstpointer a)
74 BlueSkyCloudID *id = (BlueSkyCloudID *)a;
76 // Assume that bits in the ID are randomly chosen so that any subset of the
77 // bits can be used as a hash key.
78 return *(guint *)(&id->bytes);
81 /* Formatting of cloud log segments. This handles grouping items together
82 * before writing a batch to the cloud, handling indirection through items like
83 * the inode map, etc. */
85 BlueSkyCloudLog *bluesky_cloudlog_new(BlueSkyFS *fs)
87 BlueSkyCloudLog *log = g_new0(BlueSkyCloudLog, 1);
89 log->lock = g_mutex_new();
90 log->cond = g_cond_new();
92 log->type = LOGTYPE_UNKNOWN;
93 log->id = bluesky_cloudlog_new_id();
94 log->pointers = g_array_new(FALSE, TRUE, sizeof(BlueSkyCloudID));
95 g_atomic_int_set(&log->refcount, 1);
100 /* The reference held by the hash table does not count towards the reference
101 * count. When a new object is created, it initially has a reference count of
102 * 1 for the creator, and similarly fetching an item from the hash table will
103 * also create a reference. If the reference count drops to zero,
104 * bluesky_cloudlog_unref attempts to remove the object from the hash
105 * table--but there is a potential race since another thread might read the
106 * object from the hash table at the same time. So an object with a reference
107 * count of zero may still be resurrected, in which case we need to abort the
108 * destruction. Once the object is gone from the hash table, and if the
109 * reference count is still zero, it can actually be deleted. */
110 void bluesky_cloudlog_ref(BlueSkyCloudLog *log)
115 g_atomic_int_inc(&log->refcount);
118 void bluesky_cloudlog_unref(BlueSkyCloudLog *log)
123 if (g_atomic_int_dec_and_test(&log->refcount)) {
124 BlueSkyFS *fs = log->fs;
126 g_mutex_lock(fs->lock);
127 if (g_atomic_int_get(&log->refcount) > 0) {
128 g_mutex_unlock(fs->lock);
132 g_hash_table_remove(fs->locations, &log->id);
133 g_mutex_unlock(fs->lock);
135 g_mutex_free(log->lock);
136 g_cond_free(log->cond);
137 g_array_unref(log->pointers);
138 bluesky_string_unref(log->data);
143 /* Start a write of the object to the local log. */
144 void bluesky_cloudlog_sync(BlueSkyCloudLog *log)
146 bluesky_log_item_submit(log, log->fs->log);
149 /* Add the given entry to the global hash table containing cloud log entries.
150 * Takes ownership of the caller's reference. */
151 void bluesky_cloudlog_insert(BlueSkyCloudLog *log)
153 g_mutex_lock(log->fs->lock);
154 g_hash_table_insert(log->fs->locations, &log->id, log);
155 g_mutex_unlock(log->fs->lock);
162 uint32_t pointer_count;
163 } __attribute__((packed));
167 BlueSkyCloudPointer location;
168 } __attribute__((packed));
172 struct logref refs[0];
175 BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
176 BlueSkyCloudLogState *state)
178 if (log->location_flags & CLOUDLOG_CLOUD) {
179 return log->location;
182 g_print("Flushing object %s to cloud...\n",
183 bluesky_cloudlog_id_to_string(log->id));
185 for (int i = 0; i < log->pointers->len; i++) {
186 BlueSkyCloudID id = g_array_index(log->pointers, BlueSkyCloudID, i);
187 g_print(" ...checking reference %s...\n",
188 bluesky_cloudlog_id_to_string(id));
189 g_mutex_lock(log->fs->lock);
190 BlueSkyCloudLog *log2
191 = (BlueSkyCloudLog *)g_hash_table_lookup(log->fs->locations, &id);
193 g_assert(log2 != NULL);
194 bluesky_cloudlog_ref(log2);
195 g_mutex_unlock(log->fs->lock);
196 bluesky_cloudlog_serialize(log2, state);
197 bluesky_cloudlog_unref(log2);
200 g_mutex_lock(log->lock);
201 bluesky_cloudlog_fetch(log);
202 g_assert(log->data != NULL);
204 log->location = state->location;
205 log->location.offset = state->data->len;
207 = sizeof(struct log_header) + sizeof(BlueSkyCloudID) * 0
210 struct log_header header;
211 memcpy(header.magic, "AgI ", 4);
212 header.size = GUINT32_TO_LE(log->location.size);
214 header.pointer_count = GUINT32_TO_LE(0);
216 g_string_append_len(state->data, (const char *)&header, sizeof(header));
217 g_string_append_len(state->data, log->data->data, log->data->len);
219 log->location_flags |= CLOUDLOG_CLOUD;
220 g_mutex_unlock(log->lock);
222 return log->location;
225 static void find_inodes(gpointer key, gpointer value, gpointer user_data)
227 BlueSkyCloudLogState *state = (BlueSkyCloudLogState *)user_data;
228 BlueSkyCloudLog *item = (BlueSkyCloudLog *)value;
230 if (item->type != LOGTYPE_INODE)
233 bluesky_cloudlog_ref(item);
234 state->inode_list = g_list_prepend(state->inode_list, item);
237 void bluesky_cloudlog_write_log(BlueSkyFS *fs)
239 BlueSkyCloudLogState *state = fs->log_state;
240 if (state->data == NULL)
241 state->data = g_string_new("");
243 g_mutex_lock(fs->lock);
244 g_hash_table_foreach(fs->locations, find_inodes, state);
245 g_mutex_unlock(fs->lock);
247 while (state->inode_list != NULL) {
248 BlueSkyCloudLog *log = (BlueSkyCloudLog *)state->inode_list->data;
249 bluesky_cloudlog_serialize(log, state);
250 state->inode_list = g_list_delete_link(state->inode_list,
254 if (state->data->len > 0) {
255 g_print("Serialized %zd bytes of data to cloud\n", state->data->len);
257 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
258 async->op = STORE_OP_PUT;
259 async->key = g_strdup_printf("log-%08d-%08d",
260 state->location.directory,
261 state->location.sequence);
262 async->data = bluesky_string_new_from_gstring(state->data);
263 bluesky_store_async_submit(async);
264 bluesky_store_async_wait(async);
265 bluesky_store_async_unref(async);
267 state->location.sequence++;
268 state->location.offset = 0;
274 /* Ensure that a cloud log item is loaded in memory, and if not read it in.
275 * TODO: Make asynchronous, and make this also fetch from the cloud. Right now
276 * we only read from the log. Log item must be locked. */
277 void bluesky_cloudlog_fetch(BlueSkyCloudLog *log)
279 if (log->data != NULL)
282 g_print("Re-mapping log entry %d/%d/%d...\n",
283 log->log_seq, log->log_offset, log->log_size);
285 g_assert(log->location_flags & CLOUDLOG_JOURNAL);
287 log->data = bluesky_log_map_object(log->fs->log, log->log_seq,
288 log->log_offset, log->log_size);
290 g_cond_broadcast(log->cond);