X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcloudlog.c;h=6e57d0533247d8241aca6fb36624f82fb49a6dbe;hb=83fd6b61a6e092a22d4d5e59ed95f05f5e287f11;hp=0c5db98b5f094dbaf0e8cdc9f40167ff0ef0d729;hpb=810fdc7bdf0cd13aaa7c88d3c5af5aae24e77254;p=bluesky.git

diff --git a/bluesky/cloudlog.c b/bluesky/cloudlog.c
index 0c5db98..6e57d05 100644
--- a/bluesky/cloudlog.c
+++ b/bluesky/cloudlog.c
@@ -6,24 +6,55 @@
  * TODO: Licensing
  */
 
+#include <stdio.h>
 #include <stdint.h>
 #include <glib.h>
 #include <string.h>
 
 #include "bluesky-private.h"
 
-/* The locations hash table in the file system is used to map objects to their locations.  Objects are named using 128- */
+// Rough size limit for a log segment.  This is not a firm limit and there are
+// no absolute guarantees on the size of a log segment.
+#define CLOUDLOG_SEGMENT_SIZE (4 << 20)
 
-typedef struct {
+BlueSkyCloudID bluesky_cloudlog_new_id()
+{
     BlueSkyCloudID id;
+    bluesky_crypt_random_bytes((uint8_t *)&id.bytes, sizeof(id));
+    return id;
+}
 
-    BlueSkyCloudPointer *cloud_loc;
-} BlueSkyLocationEntry;
+gchar *bluesky_cloudlog_id_to_string(BlueSkyCloudID id)
+{
+    char buf[sizeof(BlueSkyCloudID) * 2 + 1];
+    buf[0] = '\0';
 
-BlueSkyCloudID bluesky_cloudlog_new_id()
+    for (int i = 0; i < sizeof(BlueSkyCloudID); i++) {
+        sprintf(&buf[2*i], "%02x", (uint8_t)(id.bytes[i]));
+    }
+
+    return g_strdup(buf);
+}
+
+BlueSkyCloudID bluesky_cloudlog_id_from_string(const gchar *idstr)
 {
     BlueSkyCloudID id;
-    bluesky_crypt_random_bytes((uint8_t *)&id.bytes, sizeof(id));
+    memset(&id, 0, sizeof(id));
+    for (int i = 0; i < 2*sizeof(BlueSkyCloudID); i++) {
+        char c = idstr[i];
+        if (c == '\0') {
+            g_warning("Short cloud id: %s\n", idstr);
+            break;
+        }
+        int val = 0;
+        if (c >= '0' && c <= '9')
+            val = c - '0';
+        else if (c >= 'a' && c <= 'f')
+            val = c - 'a' + 10;
+        else
+            g_warning("Bad character in cloud id: %s\n", idstr);
+        id.bytes[i / 2] += val << (i % 2 ? 0 : 4);
+    }
     return id;
 }
 
@@ -51,35 +82,90 @@ BlueSkyCloudLog *bluesky_cloudlog_new(BlueSkyFS *fs)
 {
     BlueSkyCloudLog *log = g_new0(BlueSkyCloudLog, 1);
 
+    log->lock = g_mutex_new();
+    log->cond = g_cond_new();
     log->fs = fs;
     log->type = LOGTYPE_UNKNOWN;
     log->id = bluesky_cloudlog_new_id();
+    log->links = g_array_new(FALSE, TRUE, sizeof(BlueSkyCloudLog *));
     g_atomic_int_set(&log->refcount, 1);
 
     return log;
 }
 
+/* Helper function for updating memory usage statistics for a filesystem (the
+ * cache_log_* variables).  This will increment (type=1) or decrement (type=-1)
+ * the counter associated with the current state of the cloud log item.  The
+ * item should be locked or otherwise protected from concurrent access. */
+void bluesky_cloudlog_stats_update(BlueSkyCloudLog *log, int type)
+{
+    BlueSkyFS *fs = log->fs;
+
+    if (log->location_flags & CLOUDLOG_CLOUD) {
+        g_atomic_int_add(&fs->cache_log_cloud, type);
+    } else if (log->location_flags & CLOUDLOG_JOURNAL) {
+        g_atomic_int_add(&fs->cache_log_journal, type);
+    } else if (log->pending_write & CLOUDLOG_JOURNAL) {
+        g_atomic_int_add(&fs->cache_log_journal, type);
+    } else if (log->data != NULL) {
+        g_atomic_int_add(&fs->cache_log_dirty, type);
+    }
+}
+
+/* The reference held by the hash table does not count towards the reference
+ * count.  When a new object is created, it initially has a reference count of
+ * 1 for the creator, and similarly fetching an item from the hash table will
+ * also create a reference.  If the reference count drops to zero,
+ * bluesky_cloudlog_unref attempts to remove the object from the hash
+ * table--but there is a potential race since another thread might read the
+ * object from the hash table at the same time.  So an object with a reference
+ * count of zero may still be resurrected, in which case we need to abort the
+ * destruction.  Once the object is gone from the hash table, and if the
+ * reference count is still zero, it can actually be deleted. */
 void bluesky_cloudlog_ref(BlueSkyCloudLog *log)
 {
+    if (log == NULL)
+        return;
+
     g_atomic_int_inc(&log->refcount);
 }
 
 void bluesky_cloudlog_unref(BlueSkyCloudLog *log)
 {
+    if (log == NULL)
+        return;
+
     if (g_atomic_int_dec_and_test(&log->refcount)) {
-        g_print("Cloud log refcount dropped to zero.\n");
+        BlueSkyFS *fs = log->fs;
+
+        g_mutex_lock(fs->lock);
+        if (g_atomic_int_get(&log->refcount) > 0) {
+            g_mutex_unlock(fs->lock);
+            return;
+        }
+
+        g_hash_table_remove(fs->locations, &log->id);
+        g_mutex_unlock(fs->lock);
+
+        bluesky_cloudlog_stats_update(log, -1);
+        log->type = LOGTYPE_INVALID;
+        g_mutex_free(log->lock);
+        g_cond_free(log->cond);
+        for (int i = 0; i < log->links->len; i++) {
+            BlueSkyCloudLog *c = g_array_index(log->links,
+                                               BlueSkyCloudLog *, i);
+            bluesky_cloudlog_unref(c);
+        }
+        g_array_unref(log->links);
+        bluesky_string_unref(log->data);
+        g_free(log);
     }
 }
 
 /* Start a write of the object to the local log. */
-BlueSkyLogItem *bluesky_cloudlog_sync(BlueSkyCloudLog *log)
+void bluesky_cloudlog_sync(BlueSkyCloudLog *log)
 {
-    BlueSkyLogItem *log_item = bluesky_log_item_new();
-    log_item->key = g_strdup("cloudlog");
-    log_item->data = log->data;
-    bluesky_string_ref(log->data);
-    bluesky_log_item_submit(log_item, log->fs->log);
-    return log_item;
+    bluesky_log_item_submit(log, log->fs->log);
 }
 
 /* Add the given entry to the global hash table containing cloud log entries.
@@ -90,3 +176,111 @@ void bluesky_cloudlog_insert(BlueSkyCloudLog *log)
     g_hash_table_insert(log->fs->locations, &log->id, log);
     g_mutex_unlock(log->fs->lock);
 }
+
+struct log_header {
+    char magic[4];
+    uint32_t size;
+    BlueSkyCloudID id;
+    uint32_t pointer_count;
+} __attribute__((packed));
+
+struct logref {
+    BlueSkyCloudID id;
+    BlueSkyCloudPointer location;
+} __attribute__((packed));
+
+struct log_footer {
+    char refmagic[4];
+    struct logref refs[0];
+};
+
+/* Ensure that a cloud log item is loaded in memory, and if not read it in.
+ * TODO: Make asynchronous, and make this also fetch from the cloud.  Right now
+ * we only read from the log.  Log item must be locked. */
+void bluesky_cloudlog_fetch(BlueSkyCloudLog *log)
+{
+    if (log->data != NULL)
+        return;
+
+    g_assert((log->location_flags | log->pending_write) & CLOUDLOG_JOURNAL);
+
+    bluesky_cloudlog_stats_update(log, -1);
+    log->data = bluesky_log_map_object(log->fs->log, log->log_seq,
+                                       log->log_offset, log->log_size);
+    bluesky_cloudlog_stats_update(log, 1);
+
+    g_cond_broadcast(log->cond);
+}
+
+BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
+                                               BlueSkyFS *fs)
+{
+    BlueSkyCloudLogState *state = fs->log_state;
+
+    if (log->location_flags & CLOUDLOG_CLOUD) {
+        return log->location;
+    }
+
+    for (int i = 0; i < log->links->len; i++) {
+        BlueSkyCloudLog *ref = g_array_index(log->links,
+                                             BlueSkyCloudLog *, i);
+        if (ref != NULL)
+            bluesky_cloudlog_serialize(ref, fs);
+    }
+
+    g_mutex_lock(log->lock);
+    bluesky_cloudlog_fetch(log);
+    g_assert(log->data != NULL);
+
+    bluesky_cloudlog_stats_update(log, -1);
+
+    log->location = state->location;
+    log->location.offset = state->data->len;
+    log->location.size
+        = sizeof(struct log_header) + sizeof(BlueSkyCloudID) * 0
+           + log->data->len;
+
+    struct log_header header;
+    memcpy(header.magic, "AgI ", 4);
+    header.size = GUINT32_TO_LE(log->location.size);
+    header.id = log->id;
+    header.pointer_count = GUINT32_TO_LE(0);
+
+    g_string_append_len(state->data, (const char *)&header, sizeof(header));
+    g_string_append_len(state->data, log->data->data, log->data->len);
+
+    log->location_flags |= CLOUDLOG_CLOUD;
+    bluesky_cloudlog_stats_update(log, 1);
+    g_mutex_unlock(log->lock);
+
+    if (state->data->len > CLOUDLOG_SEGMENT_SIZE)
+        bluesky_cloudlog_flush(fs);
+
+    return log->location;
+}
+
+/* Finish up a partially-written cloud log segment and flush it to storage. */
+void bluesky_cloudlog_flush(BlueSkyFS *fs)
+{
+    BlueSkyCloudLogState *state = fs->log_state;
+    if (state->data == NULL || state->data->len == 0)
+        return;
+
+    /* TODO: Append some type of commit record to the log segment? */
+
+    g_print("Serializing %zd bytes of data to cloud\n", state->data->len);
+
+    BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
+    async->op = STORE_OP_PUT;
+    async->key = g_strdup_printf("log-%08d-%08d",
+                                 state->location.directory,
+                                 state->location.sequence);
+    async->data = bluesky_string_new_from_gstring(state->data);
+    bluesky_store_async_submit(async);
+    bluesky_store_async_wait(async);
+    bluesky_store_async_unref(async);
+
+    state->location.sequence++;
+    state->location.offset = 0;
+    state->data = g_string_new("");
+}