Refactor streaming replication worker child process.

Refactor the code to create external command line string using
StringInfo modules.

Author: Tatsuo Ishii <ishii@postgresql.org>
Reviewed-by: Nadav Shatz <nadav@tailorbrands.com>

diff --git a/src/streaming_replication/pool_worker_child.c b/src/streaming_replication/pool_worker_child.c
index ee4796437124c51c6a6deaebd87ad3448faff28d..311b638658e66ebb56162ad9fa4392315b2df64e 100644 (file)
--- a/src/streaming_replication/pool_worker_child.c
+++ b/src/streaming_replication/pool_worker_child.c
@@ -692,7 +692,6 @@ check_replication_time_lag_with_cmd(void)
        char       *temp_token;
        char       *endptr;
        char       *ident;
-       const char *base_command;
        double          delay_ms;
        uint64          delay;
        uint64          delay_threshold_by_time;
@@ -700,8 +699,6 @@ check_replication_time_lag_with_cmd(void)
        int                     primary_node_id;
        int                     save_errno;
        int                     i;
-       size_t          total_len;
-       size_t          current_len;
        BackendInfo *bkinfo;
        ErrorContextCallback callback;
        int                     pipefd[2] = {-1, -1};
@@ -712,6 +709,7 @@ check_replication_time_lag_with_cmd(void)
        ssize_t         bytes_read;
        int                     status;
        int                     num_replicas;
+       StringInfoData strbuf;
 
        if (NUM_BACKENDS <= 1)
        {
@@ -760,46 +758,19 @@ check_replication_time_lag_with_cmd(void)
        /* Execute command as current process user */
        PG_TRY();
        {
-               base_command = pool_config->replication_delay_source_cmd;
-               total_len = strlen(base_command) + 1;   /* +1 for NUL */
-
+               initStringInfo(&strbuf);
+               appendStringInfoString(&strbuf,
+                                                          pool_config->replication_delay_source_cmd);
                /* Build command with replica-only arguments (omit primary) */
-
-               /*
-                * Calculate total command length including space-separated replica
-                * identifiers
-                */
-               for (i = 0; i < NUM_BACKENDS; i++)
-               {
-                       if (i == primary_node_id)
-                               continue;               /* Skip primary node */
-
-                       ident = build_instance_identifier_for_node(i);
-
-                       total_len += 1 /* space */ + strlen(ident);
-                       pfree(ident);
-               }
-
-               command = palloc(total_len);
-               strlcpy(command, base_command, total_len);
-
-               /* Append replica identifiers */
-               current_len = strlen(command);
-
                for (i = 0; i < NUM_BACKENDS; i++)
                {
                        if (i == primary_node_id)
                                continue;               /* Skip primary node */
-
                        ident = build_instance_identifier_for_node(i);
-
-                       /* Append space and identifier */
-                       snprintf(command + current_len, total_len - current_len, " %s", ident);
-                       current_len += strlen(command + current_len);
-
+                       appendStringInfo(&strbuf, " %s", ident);
                        pfree(ident);
                }
-
+               command = strbuf.data;
                ereport(DEBUG1,
                                (errmsg("executing replication delay command: %s", command)));