support zenith_tenant

this patch adds support for zenith_tenant variable. it has similar
format as zenith_timeline. It is used in callmemaybe query to pass
tenant to pageserver and in ServerInfo structure passed to wal acceptor

Author: LizardWizzard

contrib/zenith/libpagestore.c

@@ -71,7 +71,7 @@ zenith_connect()
 	{
 		PGresult   *res;
 
-		query = psprintf("callmemaybe %s %s", zenith_timeline, callmemaybe_connstring);
+		query = psprintf("callmemaybe %s %s %s", zenith_tenant, zenith_timeline, callmemaybe_connstring);
 		res = PQexec(pageserver_conn, query);
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
 		{
@@ -81,7 +81,7 @@ zenith_connect()
 		PQclear(res);
 	}
 
-	query = psprintf("pagestream %s", zenith_timeline);
+	query = psprintf("pagestream %s %s", zenith_timeline, zenith_tenant);
 	ret = PQsendQuery(pageserver_conn, query);
 	if (ret != 1)
 		zenith_log(ERROR,
@@ -185,11 +185,11 @@ zenith_call(ZenithRequest request)
 
 
 static bool
-check_zenith_timeline(char **newval, void **extra, GucSource source)
+check_zenith_id(char **newval, void **extra, GucSource source)
 {
-	uint8		ztimelineid[16];
+	uint8		zid[16];
 
-	return **newval == '\0' || HexDecodeString(ztimelineid, *newval, 16);
+	return **newval == '\0' || HexDecodeString(zid, *newval, 16);
 }
 
 /*
@@ -223,7 +223,16 @@ _PG_init(void)
 							   "",
 							   PGC_POSTMASTER,
 							   0,	/* no flags required */
-							   check_zenith_timeline, NULL, NULL);
+							   check_zenith_id, NULL, NULL);
+
+	DefineCustomStringVariable("zenith.zenith_tenant",
+							   "Zenith tenantid the server is running on",
+							   NULL,
+							   &zenith_tenant,
+							   "",
+							   PGC_POSTMASTER,
+							   0,	/* no flags required */
+							   check_zenith_id, NULL, NULL);
 
 	DefineCustomBoolVariable("zenith.wal_redo",
 							 "start in wal-redo mode",
@@ -242,6 +251,7 @@ _PG_init(void)
 
 	/* Is there more correct way to pass CustomGUC to postgres code? */
 	zenith_timeline_walproposer = zenith_timeline;
+	zenith_tenant_walproposer = zenith_tenant;
 
 	if (wal_redo)
 	{

contrib/zenith/pagestore_client.h

@@ -90,6 +90,7 @@ extern page_server_api * page_server;
 extern char *page_server_connstring;
 extern char *callmemaybe_connstring;
 extern char *zenith_timeline;
+extern char *zenith_tenant;
 extern bool wal_redo;
 
 extern const f_smgr *smgr_zenith(BackendId backend, RelFileNode rnode);

contrib/zenith/pagestore_smgr.c

@@ -56,6 +56,7 @@ page_server_api *page_server;
 char *page_server_connstring;
 char *callmemaybe_connstring;
 char *zenith_timeline;
+char *zenith_tenant;
 bool wal_redo = false;
 
 char const *const ZenithMessageStr[] =

src/backend/replication/walproposer.c

@@ -221,6 +221,7 @@ HandleWalKeeperResponse(void)
 }
 
 char *zenith_timeline_walproposer = NULL;
+char *zenith_tenant_walproposer = NULL;
 
 /*
  * WAL proposer bgworeker entry point
@@ -285,6 +286,13 @@ WalProposerMain(Datum main_arg)
 	if (*zenith_timeline_walproposer != '\0' &&
 	 !HexDecodeString(serverInfo.ztimelineid, zenith_timeline_walproposer, 16))
 		elog(FATAL, "Could not parse zenith.zenith_timeline, %s", zenith_timeline_walproposer);
+	
+	if (!zenith_tenant_walproposer)
+		elog(FATAL, "zenith.zenith_tenant is not provided");
+	if (*zenith_tenant_walproposer != '\0' &&
+	 !HexDecodeString(serverInfo.ztenantid, zenith_tenant_walproposer, 16))
+		elog(FATAL, "Could not parse zenith.zenith_tenant, %s", zenith_tenant_walproposer);
+
 	serverInfo.protocolVersion = SK_PROTOCOL_VERSION;
 	pg_strong_random(&serverInfo.nodeId.uuid, sizeof(serverInfo.nodeId.uuid));
 	serverInfo.systemId = GetSystemIdentifier();

src/include/replication/walproposer.h

@@ -23,6 +23,7 @@ struct WalMessage;
 typedef struct WalMessage WalMessage;
 
 extern char *zenith_timeline_walproposer;
+extern char *zenith_tenant_walproposer;
 
 /* WAL safekeeper state */
 typedef enum
@@ -59,6 +60,7 @@ typedef struct ServerInfo
 	XLogRecPtr walEnd;
     TimeLineID timeline;
 	int        walSegSize;
+	uint8      ztenantid[16];
 } ServerInfo;
 
 /*