Implement load database dumps from S3. We already save.

Former-commit-id: a45f212693956a6fb1aacf465d88e940bbbfd56f

src/debug.c

@@ -362,7 +362,7 @@ NULL
         }
         emptyDb(-1,EMPTYDB_NO_FLAGS,NULL);
         protectClient(c);
-        int ret = rdbLoad(server.rdb_filename,NULL);
+        int ret = rdbLoad(NULL);
         unprotectClient(c);
         if (ret != C_OK) {
             addReplyError(c,"Error trying to load the RDB dump");

src/rdb-s3.cpp

@@ -48,4 +48,64 @@ extern "C" int rdbSaveS3(char *s3bucket, rdbSaveInfo *rsi)
         serverLog(LL_NOTICE,"DB saved on AWS S3");
         
     return (status == EXIT_SUCCESS) ? C_OK : C_ERR;
-}
+}
+
+
+int rdbLoadS3Core(int fd, rdbSaveInfo *rsi) 
+{
+    FILE *fp;
+    rio rdb;
+    int retval;
+
+    if ((fp = fdopen(fd, "rb")) == NULL) return C_ERR;
+    startLoading(fp);
+    rioInitWithFile(&rdb,fileno(fp));
+    retval = rdbLoadRio(&rdb,rsi,0);
+    fclose(fp);
+    stopLoading();
+    return retval;
+}
+
+int rdbLoadS3(char *s3bucket, rdbSaveInfo *rsi)
+{
+    int status = EXIT_FAILURE;
+    int fd[2];
+    if (pipe(fd) != 0)
+        return C_ERR;
+
+    pid_t pid = fork();
+    if (pid < 0)
+    {
+        close(fd[0]);
+        close(fd[1]);
+        return C_ERR;
+    }
+
+    if (pid == 0)
+    {
+        // child process
+        dup2(fd[1], STDOUT_FILENO);
+        close(fd[1]);
+        close(fd[0]);
+        execlp("aws", "aws", "s3", "cp", s3bucket, "-", nullptr);
+        exit(EXIT_FAILURE);
+    }
+    else
+    {
+        close(fd[1]);
+        if (rdbLoadS3Core(fd[0], rsi) != C_OK)
+        {
+            close(fd[0]);
+            return C_ERR;
+        }
+        close(fd[0]);
+        waitpid(pid, &status, 0);
+    }
+    
+    if (status != EXIT_SUCCESS)
+        serverLog(LL_WARNING, "Failed to load DB from AWS S3");
+    else
+        serverLog(LL_NOTICE,"DB loaded from AWS S3");
+        
+    return (status == EXIT_SUCCESS) ? C_OK : C_ERR;
+}

src/rdb.c

@@ -2097,6 +2097,19 @@ eoferr: /* unexpected end of file is handled here with a fatal exit */
     return C_ERR; /* Just to avoid warning */
 }
 
+int rdbLoadFile(char *filename, rdbSaveInfo *rsi);
+int rdbLoad(rdbSaveInfo *rsi)
+{
+    int err = C_ERR;
+    if (server.rdb_filename != NULL)
+        err = rdbLoadFile(server.rdb_filename, rsi);
+
+    if ((err == C_ERR) && server.rdb_s3bucketpath != NULL)
+        err = rdbLoadS3(server.rdb_s3bucketpath, rsi);
+
+    return err;
+}
+
 /* Like rdbLoadRio() but takes a filename instead of a rio stream. The
  * filename is open for reading and a rio stream object created in order
  * to do the actual loading. Moreover the ETA displayed in the INFO
@@ -2104,7 +2117,7 @@ eoferr: /* unexpected end of file is handled here with a fatal exit */
  *
  * If you pass an 'rsi' structure initialied with RDB_SAVE_OPTION_INIT, the
  * loading code will fiil the information fields in the structure. */
-int rdbLoad(char *filename, rdbSaveInfo *rsi) {
+int rdbLoadFile(char *filename, rdbSaveInfo *rsi) {
     FILE *fp;
     rio rdb;
     int retval;

src/rdb.h

@@ -135,7 +135,7 @@ uint64_t rdbLoadLen(rio *rdb, int *isencoded);
 int rdbLoadLenByRef(rio *rdb, int *isencoded, uint64_t *lenptr);
 int rdbSaveObjectType(rio *rdb, robj *o);
 int rdbLoadObjectType(rio *rdb);
-int rdbLoad(char *filename, rdbSaveInfo *rsi);
+int rdbLoad(rdbSaveInfo *rsi);
 int rdbSaveBackground(rdbSaveInfo *rsi);
 int rdbSaveToSlavesSockets(rdbSaveInfo *rsi);
 void rdbRemoveTempFile(pid_t childpid);
@@ -143,6 +143,7 @@ int rdbSave(rdbSaveInfo *rsi);
 int rdbSaveFile(char *filename, rdbSaveInfo *rsi);
 int rdbSaveFd(int fd, rdbSaveInfo *rsi);
 int rdbSaveS3(char *path, rdbSaveInfo *rsi);
+int rdbLoadS3(char *path, rdbSaveInfo *rsi);
 ssize_t rdbSaveObject(rio *rdb, robj *o);
 size_t rdbSavedObjectLen(robj *o);
 robj *rdbLoadObject(int type, rio *rdb);

src/replication.cpp

@@ -1334,7 +1334,7 @@ void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) {
         aeDeleteFileEvent(el,server.repl_transfer_s,AE_READABLE);
         serverLog(LL_NOTICE, "MASTER <-> REPLICA sync: Loading DB in memory");
         rdbSaveInfo rsi = RDB_SAVE_INFO_INIT;
-        if (rdbLoad(server.rdb_filename,&rsi) != C_OK) {
+        if (rdbLoad(&rsi) != C_OK) {
             serverLog(LL_WARNING,"Failed trying to load the MASTER synchronization DB from disk");
             cancelReplicationHandshake();
             /* Re-enable the AOF if we disabled it earlier, in order to restore

src/server.cpp

@@ -4668,9 +4668,9 @@ void loadDataFromDisk(void) {
     if (server.aof_state == AOF_ON) {
         if (loadAppendOnlyFile(server.aof_filename) == C_OK)
             serverLog(LL_NOTICE,"DB loaded from append only file: %.3f seconds",(float)(ustime()-start)/1000000);
-    } else if (server.rdb_filename != NULL) {
+    } else if (server.rdb_filename != NULL || server.rdb_s3bucketpath != NULL) {
         rdbSaveInfo rsi = RDB_SAVE_INFO_INIT;
-        if (rdbLoad(server.rdb_filename,&rsi) == C_OK) {
+        if (rdbLoad(&rsi) == C_OK) {
             serverLog(LL_NOTICE,"DB loaded from disk: %.3f seconds",
                 (float)(ustime()-start)/1000000);