Add the 'tries' parameter to the raftable_set() call.

Author: kvap

contrib/raftable/README

@@ -56,7 +56,7 @@ C API:
 
 SQL API:
 	-- set
-	raftable(key varchar(64), value text);
+	raftable(key varchar(64), value text, tries int);
 
 	-- get
 	raftable(key varchar(64)) returns text;

contrib/raftable/raftable--1.0.sql

@@ -8,7 +8,7 @@ AS 'MODULE_PATHNAME','raftable_sql_get'
 LANGUAGE C;
 
 -- set
-CREATE FUNCTION raftable(key varchar(64), value text)
+CREATE FUNCTION raftable(key varchar(64), value text, tries int)
 RETURNS void
 AS 'MODULE_PATHNAME','raftable_sql_set'
 LANGUAGE C;

contrib/raftable/raftable.c

@@ -165,11 +165,17 @@ raftable_sql_get(PG_FUNCTION_ARGS)
 		PG_RETURN_NULL();
 }
 
-void raftable_set(char *key, char *value)
+bool raftable_set(char *key, char *value, int tries)
 {
 	RaftableUpdate *ru;
 	size_t size = sizeof(RaftableUpdate);
 	int keylen, vallen = 0;
+	bool ok = false;
+
+	if (tries <= 0)
+	{
+		elog(ERROR, "raftable set should be called with 'tries' > 0");
+	}
 
 	keylen = strlen(key) + 1;
 	if (value) vallen = strlen(value) + 1;
@@ -188,60 +194,67 @@ void raftable_set(char *key, char *value)
 	memcpy(f->data, key, keylen);
 	memcpy(f->data + keylen, value, vallen);
 
-	bool ok = false;
-	while (!ok)
+tryagain:
+	if (tries--)
 	{
-		fprintf(stderr, "trying to send an update to the leader\n");
 		int s = get_connection();
-		int sent = 0;
-		ok = true;
+		int sent = 0, recved = 0;
+		int status;
 
 		if (write(s, &size, sizeof(size)) != sizeof(size))
 		{
 			disconnect_leader();
-			fprintf(stderr, "failed to send the update size to the leader\n");
-			ok = false;
-			continue;
+			elog(WARNING, "failed[%d] to send the update size to the leader", tries);
+			goto tryagain;
 		}
 
-		while (ok && (sent < size))
+		while (sent < size)
 		{
 			int newbytes = write(s, (char *)ru + sent, size - sent);
 			if (newbytes == -1)
 			{
 				disconnect_leader();
-				fprintf(stderr, "failed to send the update to the leader\n");
-				ok = false;
+				elog(WARNING, "failed[%d] to send the update to the leader", tries);
+				goto tryagain;
 			}
 			sent += newbytes;
 		}
 
-		if (ok)
+		recved = read(s, &status, sizeof(status));
+		if (recved != sizeof(status))
 		{
-			int status;
-			int recved = read(s, &status, sizeof(status));
-			if (recved != sizeof(status))
-			{
-				disconnect_leader();
-				fprintf(stderr, "failed to recv the update status from the leader\n");
-				ok = false;
-			}
+			disconnect_leader();
+			elog(WARNING, "failed to recv the update status from the leader\n");
+			goto tryagain;
 		}
+		goto success;
+	}
+	else
+	{
+		goto failure;
 	}
 
+failure:
+	elog(WARNING, "failed all tries to set raftable value\n");
+	pfree(ru);
+	return false;
+
+success:
 	pfree(ru);
+	return true;
 }
 
 Datum
 raftable_sql_set(PG_FUNCTION_ARGS)
 {
 	char *key = text_to_cstring(PG_GETARG_TEXT_P(0));
+	int tries = PG_GETARG_INT32(2);
 	if (PG_ARGISNULL(1))
-		raftable_set(key, NULL);
+		raftable_set(key, NULL, tries);
 	else
 	{
 		char *value = text_to_cstring(PG_GETARG_TEXT_P(1));
-		raftable_set(key, value);
+		raftable_set(key, value, tries);
 		pfree(value);
 	}
 	pfree(key);

contrib/raftable/raftable.h

@@ -6,9 +6,10 @@ char *raftable_get(char *key);
 
 /*
  * Adds/updates value by key. Returns when the value gets replicated.
- * Storing NULL will delete the item from the table.
+ * Storing NULL will delete the item from the table. Give up after 'tries'
+ * tries have failed.
  */
-void raftable_set(char *key, char *value);
+bool raftable_set(char *key, char *value, int tries);
 
 /*
  * Iterates over all items in the table, calling func(key, value, arg)

contrib/raftable/t/000_basic.pl

@@ -68,11 +68,13 @@ sub start_nodes
 	world => genstr(3000),
 );
 
-$able->psql('postgres', "select raftable('hello', '$tests{hello}');");
-$baker->psql('postgres', "select raftable('and', '$tests{and}');");
-$charlie->psql('postgres', "select raftable('goodbye', '$tests{goodbye}');");
+my $tries = 10;
+
+$able->psql('postgres', "select raftable('hello', '$tests{hello}', $tries);");
+$baker->psql('postgres', "select raftable('and', '$tests{and}', $tries);");
+$charlie->psql('postgres', "select raftable('goodbye', '$tests{goodbye}', $tries);");
 $baker->stop;
-$able->psql('postgres', "select raftable('world', '$tests{world}');");
+$able->psql('postgres', "select raftable('world', '$tests{world}', $tries);");
 
 $baker->start;
 sleep(5);