1 /* Blue Sky: File Systems in the Cloud
3 * Copyright (C) 2010 The Regents of the University of California
4 * Written by Michael Vrable <mvrable@cs.ucsd.edu>
16 #include "bluesky-private.h"
18 /* Proxy component of the file system cleaner. This consists effectively of
19 * code for merging multiple versions of the file system logs: that generated
20 * by us and that generated by the in-cloud cleaner. Other logic, such as for
21 * rewriting log segments where needed and deleting old segments, is handled by
22 * the in-cloud cleaner component. */
24 /* A specialized function for loading an object from the cloud, used just by
25 * the cleaner. When the cleaner runs, it will produce new objects that have
26 * the same object ID as before, differing only in the outgoing link locations
27 * as a result of cleaning. We can't use the normal functions for loading
28 * objects since those can only deal with one version of an object. Instead,
29 * we load the cleaned object with this function, and then merge the state into
30 * the official object as needed.
32 * The bluesky_cleaner_deserialize function is like
33 * bluesky_deserialize_cloudlog, but does a more limited deserialization and
34 * keeps the returned item entirely separate from any in-memory BlueSkyCloudLog
38 BlueSkyCloudLogType type;
40 BlueSkyCloudPointer location;
47 BlueSkyCloudPointer location;
50 static BlueSkyCleanerItem *bluesky_cleaner_deserialize(BlueSkyRCStr *raw)
52 const char *data = raw->data;
53 size_t len = raw->len;
54 const char *data1, *data2, *data3;
55 size_t len1, len2, len3;
58 if (len < sizeof(struct cloudlog_header)
59 || memcmp(data, CLOUDLOG_MAGIC, 4) != 0)
61 g_warning("Deserializing garbage cloud log item from cleaner!");
65 struct cloudlog_header *header = (struct cloudlog_header *)data;
66 len1 = GUINT32_FROM_LE(header->size1);
67 len2 = GUINT32_FROM_LE(header->size2);
68 len3 = GUINT32_FROM_LE(header->size3);
69 data1 = data + sizeof(struct cloudlog_header);
72 g_assert(data3 + len3 - data <= len);
74 BlueSkyCleanerItem *item = g_new0(BlueSkyCleanerItem, 1);
75 item->type = header->type - '0';
76 item->inum = GUINT64_FROM_LE(header->inum);
77 memcpy(&item->id, &header->id, sizeof(BlueSkyCloudID));
79 int link_count = len2 / sizeof(BlueSkyCloudID);
80 g_print("Outgoing links: %d\n", link_count);
81 item->links = g_array_new(FALSE, TRUE, sizeof(BlueSkyCleanerLink));
82 for (int i = 0; i < link_count; i++) {
83 BlueSkyCleanerLink link;
85 g_assert(len2 >= sizeof(link.id));
86 memcpy(&link.id, data2, sizeof(link.id));
87 data2 += sizeof(link.id); len2 -= sizeof(link.id);
89 g_assert(len3 >= sizeof(link.location));
90 memcpy(&link.location, data3, sizeof(link.location));
91 data3 += sizeof(link.location); len3 -= sizeof(link.location);
93 g_array_append_val(item->links, link);
99 static void bluesky_cleaner_item_free(BlueSkyCleanerItem *item)
103 g_array_unref(item->links);
107 /* Check the cleaner's logs to find the a more recent checkpoint record. This
108 * should be called occasionally to see if the cleaner has done any work since
110 static BlueSkyCleanerItem *bluesky_cleaner_find_checkpoint(BlueSkyFS *fs)
112 char *prefix = g_strdup_printf("log-%08d", BLUESKY_CLOUD_DIR_CLEANER);
113 char *last_segment = bluesky_store_lookup_last(fs->store, prefix);
115 if (last_segment == NULL)
118 g_print("Last cloud log segment: %s\n", last_segment);
119 int seq = atoi(last_segment + 13);
120 g_free(last_segment);
122 if (seq <= fs->log_state->latest_cleaner_seq_seen)
125 g_print("New log segment appeared in cleaner directory: %d\n", seq);
127 BlueSkyCacheFile *cachefile;
128 cachefile = bluesky_cachefile_lookup(fs, BLUESKY_CLOUD_DIR_CLEANER, seq,
130 while (!cachefile->complete)
131 g_cond_wait(cachefile->cond, cachefile->lock);
133 g_print("Downloaded latest cleaner segment.\n");
135 int64_t offset = -1, length = 0;
137 const BlueSkyRangesetItem *item;
138 item = bluesky_rangeset_lookup_next(cachefile->items, offset + 1);
141 offset = item->start;
142 length = item->length;
148 g_print("Found a cleaner checkpoint record.\n");
150 BlueSkyRCStr *data = bluesky_cachefile_map_raw(cachefile, offset, length);
151 bluesky_cachefile_unref(cachefile);
152 g_mutex_unlock(cachefile->lock);
154 BlueSkyCleanerItem *checkpoint = bluesky_cleaner_deserialize(data);
155 bluesky_string_unref(data);
160 static BlueSkyCleanerItem *cleaner_load_item(BlueSkyFS *fs,
161 BlueSkyCloudPointer location)
163 g_print("Loading item %d/%d/%d...\n", location.directory, location.sequence, location.offset);
165 BlueSkyCacheFile *cachefile;
166 cachefile = bluesky_cachefile_lookup(fs, location.directory,
167 location.sequence, TRUE);
168 while (!cachefile->complete)
169 g_cond_wait(cachefile->cond, cachefile->lock);
171 /* TODO: Ought to check that we are loading an item which validated? */
172 BlueSkyRCStr *data = bluesky_cachefile_map_raw(cachefile, location.offset,
174 bluesky_cachefile_unref(cachefile);
175 g_mutex_unlock(cachefile->lock);
177 BlueSkyCleanerItem *item = bluesky_cleaner_deserialize(data);
178 bluesky_string_unref(data);
183 /* Does the item at the given cloud location from the cleaner need merging? An
184 * item in the primary log does not need to be merged, as by definition we
185 * already know about it. Similarly, old items in the cleaner's log--those
186 * that we have already seen from a previous merge--do not need to be mergd
188 gboolean needs_merging(BlueSkyFS *fs, BlueSkyCloudPointer location)
190 if (location.directory == BLUESKY_CLOUD_DIR_PRIMARY)
196 void bluesky_cleaner_merge(BlueSkyFS *fs)
198 BlueSkyCleanerItem *checkpoint = bluesky_cleaner_find_checkpoint(fs);
200 if (checkpoint == NULL) {
201 g_warning("Unable to load cleaner checkpoint record!");
205 /* Iterate over each of the inode map sections in the checkpoint */
206 for (int i = 0; i < checkpoint->links->len; i++) {
207 BlueSkyCleanerLink *link = &g_array_index(checkpoint->links,
208 BlueSkyCleanerLink, i);
209 /*if (!needs_merging(fs, link->location))
212 BlueSkyCleanerItem *imap = cleaner_load_item(fs, link->location);
214 g_warning("Unable to load cleaner inode map");
218 /* Iterate over all inodes found in the inode map section */
219 for (int j = 0; j < imap->links->len; j++) {
220 BlueSkyCleanerLink *link = &g_array_index(imap->links,
221 BlueSkyCleanerLink, j);
222 BlueSkyCleanerItem *inode = cleaner_load_item(fs, link->location);
224 g_print("Got inode %"PRIu64"\n", inode->inum);
226 bluesky_cleaner_item_free(inode);
229 bluesky_cleaner_item_free(imap);
232 bluesky_cleaner_item_free(checkpoint);