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multimaster.c
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/*-----------------------------------------------------------------------------
* multimaster.c
*
* Multimaster based on logical replication
*
* Copyright (c) 2016-2020, Postgres Professional
*
*-----------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/relscan.h"
#include "access/table.h"
#include "access/tableam.h"
#include "access/heapam.h"
#include "access/xact.h"
#include "nodes/makefuncs.h"
#include "replication/origin.h"
#include "replication/slot.h"
#include "replication/logical.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "utils/builtins.h"
#include "commands/publicationcmds.h"
#include "commands/subscriptioncmds.h"
#include "executor/spi.h"
#include "catalog/pg_type.h"
#include "tcop/tcopprot.h"
#include "catalog/pg_subscription.h"
#include "catalog/pg_publication.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "commands/defrem.h"
#include "replication/message.h"
#include "utils/pg_lsn.h"
#include "replication/walreceiver.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "catalog/pg_authid.h"
#include "libpq/pqformat.h"
#include "multimaster.h"
#include "ddd.h"
#include "ddl.h"
#include "state.h"
#include "logger.h"
#include "commit.h"
#include "messaging.h"
#include "syncpoint.h"
#include "compat.h"
typedef enum
{
MTM_STATE_LOCK_ID
} MtmLockIds;
typedef struct
{
TimestampTz last_timestamp;
slock_t mutex;
} MtmTime;
static MtmTime *mtm_time;
#define MTM_SHMEM_SIZE (8*1024*1024)
void _PG_init(void);
void _PG_fini(void);
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(mtm_after_node_create);
PG_FUNCTION_INFO_V1(mtm_after_node_drop);
PG_FUNCTION_INFO_V1(mtm_join_node);
PG_FUNCTION_INFO_V1(mtm_init_cluster);
PG_FUNCTION_INFO_V1(mtm_get_bgwpool_stat);
PG_FUNCTION_INFO_V1(mtm_ping);
PG_FUNCTION_INFO_V1(mtm_hold_backends);
PG_FUNCTION_INFO_V1(mtm_release_backends);
PG_FUNCTION_INFO_V1(mtm_check_query);
#if 0
static size_t MtmGetTransactionStateSize(void);
static void MtmSerializeTransactionState(void *ctx);
static void MtmDeserializeTransactionState(void *ctx);
#endif
#ifdef PGPRO_EE
static void *MtmSuspendTransaction(void);
static void MtmResumeTransaction(void *ctx);
#endif
static void release_pb_holders_xact_cb(XactEvent event, void *arg);
static void MtmShmemStartup(void);
static void launcher_init(void);
void launcher_main(Datum main_arg);
void drop_node_entry(int node_id);
MtmShared *Mtm;
MemoryContext MtmApplyContext;
char const * const MtmTxRequestValueMnem[] = {
"MTReq_Abort",
"MTReq_Commit",
"MTReq_Precommit",
"MTReq_Preabort",
"MTReq_Status"
};
char const *const MtmMessageTagMnem[] =
{
"MtmPrepareResponse",
"Mtm2AResponse",
"MtmTxRequest",
"MtmTxStatusResponse",
"MtmHeartbeat",
"MtmGenVoteRequest",
"MtmGenVoteResponse"
};
/* copied from core */
static const struct config_enum_entry server_message_level_options[] = {
{"debug5", DEBUG5, false},
{"debug4", DEBUG4, false},
{"debug3", DEBUG3, false},
{"debug2", DEBUG2, false},
{"debug1", DEBUG1, false},
{"debug", DEBUG2, true},
{"info", INFO, false},
{"notice", NOTICE, false},
{"warning", WARNING, false},
{"error", ERROR, false},
{"log", LOG, false},
{"fatal", FATAL, false},
{"panic", PANIC, false},
{NULL, 0, false}
};
/* keep it in sync with MtmLogTag */
MtmLogGuc mtm_log_gucs[] = {
{"TxTrace", DEBUG3, 0},
{"TxFinish", DEBUG2, 0},
{"CoordinatorTrace", DEBUG3, 0},
{"DmqStateIntermediate", DEBUG2, 0},
{"DmqStateFinal", LOG, 0},
{"DmqTraceOutgoing", DEBUG3, 0},
{"DmqTraceIncoming", DEBUG3, 0},
{"DmqTraceShmMq", DEBUG3, 0},
{"DmqPqTiming", DEBUG4, 0},
{"ResolverState", LOG, 0},
{"ResolverTx", LOG, 0},
{"ResolverTasks", LOG, 0},
{"StatusRequest", LOG, 0},
{"BgwPoolEvent", LOG, 0},
{"BgwPoolEventDebug", DEBUG2, 0},
{"DeadlockCheck", DEBUG2, 0},
{"DeadlockUpdate", DEBUG2, 0},
{"DeadlockSerialize", DEBUG2, 0},
{"DDLStmtOutgoing", LOG, 0},
{"DDLStmtIncoming", LOG, 0},
{"DDLProcessingTrace", DEBUG2, 0},
{"ProtoTraceFilter", DEBUG3, 0},
{"ProtoTraceSender", DEBUG3, 0},
{"ProtoTraceMessage", DEBUG2, 0},
{"ProtoTraceState", LOG, 0},
{"ReceiverState", LOG, 0},
{"ReceiverStateDebug", DEBUG2, 0},
{"ReceiverFilter", DEBUG2, 0},
{"ApplyMessage", DEBUG2, 0},
{"ApplyTrace", DEBUG2, 0},
{"ApplyError", LOG, 0},
{"ApplyBgwFinish", LOG, 0},
{"ReceiverFeedback", DEBUG2, 0},
{"StateMessage", LOG, 0},
{"StateSwitch", LOG, 0},
{"StateDebug", DEBUG2, 0},
{"SyncpointCreated", LOG, 0},
{"SyncpointApply", LOG, 0},
{"NodeMgmt", LOG, 0},
{NULL, 0, 0} /* end of list marker */
};
/* XXX */
bool MtmBackgroundWorker;
/*
* Maximal size of transaction after which transaction is written to the disk.
* Also defines bgwpool shared queue size (See BgwPoolStart routine).
*/
int MtmTransSpillThreshold;
int MtmConnectTimeout;
int MtmHeartbeatSendTimeout;
int MtmHeartbeatRecvTimeout;
char *MtmRefereeConnStr;
bool MtmBreakConnection;
bool MtmWaitPeerCommits;
bool MtmNo3PC;
bool MtmBinaryBasetypes;
bool mtm_config_valid;
static shmem_startup_hook_type PreviousShmemStartupHook;
/*
* If you get really bored one day, you may try hardware-accelerated popcount
* here and see if anything changes (it won't, I'm sure).
*/
int
popcount(nodemask_t mask)
{
int i,
count = 0;
for (i = 0; i < MTM_MAX_NODES; i++)
{
if (BIT_CHECK(mask, i))
count++;
}
return count;
}
int
first_set_bit(nodemask_t mask)
{
int i;
for (i = 0; i < MTM_MAX_NODES; i++)
{
if (BIT_CHECK(mask, i))
return i;
}
return -1;
}
/* is submask \in mask? */
bool
is_submask(nodemask_t submask, nodemask_t mask)
{
int i;
for (i = 0; i < MTM_MAX_NODES; i++)
{
if (BIT_CHECK(submask, i) && !BIT_CHECK(mask, i))
return false;
}
return true;
}
/* XXXX: allocate in context and clean it */
char *
maskToString(nodemask_t mask)
{
char *strMask = palloc0(MTM_MAX_NODES + 1);
int i;
int last_setbit = 0; /* truncate all suffix zeros */
for (i = 0; i < MTM_MAX_NODES; i++)
{
strMask[i] = BIT_CHECK(mask, i) ? '1' : '0';
if (BIT_CHECK(mask, i))
last_setbit = i;
}
strMask[last_setbit + 1] = '\0';
return strMask;
}
/*
* -------------------------------------------
* System time manipulation functions
* -------------------------------------------
*/
TimestampTz
MtmGetIncreasingTimestamp()
{
TimestampTz now = GetCurrentTimestamp();
/*
* Don't let time move backward; if it hasn't advanced, use incremented
* last value.
*/
SpinLockAcquire(&mtm_time->mutex);
if (now <= mtm_time->last_timestamp)
now = ++mtm_time->last_timestamp;
else
mtm_time->last_timestamp = now;
SpinLockRelease(&mtm_time->mutex);
return now;
}
void
MtmSleep(int64 usec)
{
TimestampTz waketm = GetCurrentTimestamp() + usec;
for (;;)
{
TimestampTz sleepfor;
CHECK_FOR_INTERRUPTS();
sleepfor = waketm - GetCurrentTimestamp();
if (sleepfor < 0)
break;
WaitLatch(MyLatch,
WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
sleepfor / 1000.0, WAIT_EVENT_BGWORKER_STARTUP);
}
}
/*
* These were once used to setup mtm state in parallel workers, but as long as
* they are read-only we don't really need it (historically it imported csn
* snapshot).
*/
#if 0
static size_t
MtmGetTransactionStateSize(void)
{
return sizeof(MtmTx);
}
static void
MtmSerializeTransactionState(void *ctx)
{
memcpy(ctx, &MtmTx, sizeof(MtmTx));
}
static void
MtmDeserializeTransactionState(void *ctx)
{
memcpy(&MtmTx, ctx, sizeof(MtmTx));
}
#endif
/*
* ATX compatibility support.
*/
#ifdef PGPRO_EE
static void *
MtmSuspendTransaction(void)
{
MtmCurrentTrans *ctx = malloc(sizeof(MtmCurrentTrans));
*ctx = MtmTx;
MtmTxAtxLevel++;
temp_schema_init();
CallXactCallbacks(XACT_EVENT_START);
return ctx;
}
static void
MtmResumeTransaction(void *ctx)
{
MtmTx = *(MtmCurrentTrans *) ctx;
free(ctx);
MtmTxAtxLevel--;
temp_schema_init();
}
#endif
/*
* Perform initialization of multimaster state.
* This function is called from shared memory startup hook (after completion of initialization of shared memory)
*/
static void
MtmSharedShmemStartup()
{
bool found;
int i;
LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
mtm_time = (MtmTime *) ShmemInitStruct("mtm_time", sizeof(MtmTime), &found);
if (!found)
{
mtm_time->last_timestamp = 0;
SpinLockInit(&mtm_time->mutex);
}
Mtm = (MtmShared *) ShmemInitStruct(MULTIMASTER_NAME, sizeof(MtmShared), &found);
if (!found)
{
MemSet(Mtm, 0, sizeof(MtmShared));
Mtm->localTablesHashLoaded = false;
Mtm->latestSyncpoint = InvalidXLogRecPtr;
/*
* Enable sign for the database will be set at the MtmIsEnabled()
* function call when the "multimaster" extension existence will be
* detected.
*/
Mtm->IsEnabled = false;
Mtm->DatabaseId = InvalidOid;
Mtm->lock = &(GetNamedLWLockTranche(MULTIMASTER_NAME)[0].lock);
Mtm->syncpoint_lock = &(GetNamedLWLockTranche(MULTIMASTER_NAME)[1].lock);
pg_atomic_init_u64(&Mtm->configured_mask, 0);
ConditionVariableInit(&Mtm->receiver_barrier_cv);
Mtm->resolver_pid = InvalidPid;
for (i = 0; i < MTM_MAX_NODES; i++)
{
Mtm->peers[i].walsender_pid = InvalidPid;
Mtm->peers[i].dmq_dest_id = -1;
Mtm->peers[i].dmq_receiver_pid = InvalidPid;
pg_atomic_init_u64(&Mtm->peers[i].horizon, InvalidXLogRecPtr);
/*
* XXX Assume that MaxBackends is the same at each node of
* multimaster
*/
Mtm->pools[i].txlist.store = ShmemAlloc(sizeof(txlelem_t) * MaxBackends);
Mtm->pools[i].txlist.size = MaxBackends;
}
Mtm->walreceivers_mask = 0;
Mtm->walsenders_mask = 0;
}
RegisterXactCallback(MtmXactCallback, NULL);
LWLockRelease(AddinShmemInitLock);
}
static void
MtmShmemStartup(void)
{
if (PreviousShmemStartupHook)
PreviousShmemStartupHook();
MtmDDLReplicationShmemStartup();
MtmStateShmemStartup();
MtmSharedShmemStartup();
MtmGlobalTxShmemStartup();
}
void
_PG_init(void)
{
int i;
/*
* In order to create our shared memory area, we have to be loaded via
* shared_preload_libraries. If not, fall out without hooking into any of
* the main system. (We don't throw error here because it seems useful to
* allow the cs_* functions to be created even when the module isn't
* active. The functions must protect themselves against being called
* then, however.)
*/
if (!process_shared_preload_libraries_in_progress)
return;
DefineCustomIntVariable(
"multimaster.connect_timeout",
"Maximum wait for peer connection establishment, in seconds. Semantic follows libpq connect_timeout option.",
NULL,
&MtmConnectTimeout,
0,
0,
INT_MAX,
PGC_POSTMASTER,
0,
NULL,
NULL,
NULL
);
DefineCustomIntVariable(
"multimaster.heartbeat_send_timeout",
"Timeout in milliseconds of sending heartbeat messages",
"Period of broadcasting heartbeat messages",
&MtmHeartbeatSendTimeout,
200,
1,
INT_MAX,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
DefineCustomIntVariable(
"multimaster.heartbeat_recv_timeout",
"Timeout in milliseconds of receiving heartbeat messages",
"If no heartbeat message is received from node within this period, it assumed to be dead",
&MtmHeartbeatRecvTimeout,
2000,
1,
INT_MAX,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
DefineCustomIntVariable(
"multimaster.trans_spill_threshold",
"Maximal size of transaction after which transaction is written to the disk",
NULL,
&MtmTransSpillThreshold,
100 * 1024, /* 100Mb */
0,
MaxAllocSize / 1024,
PGC_SIGHUP,
GUC_UNIT_KB,
NULL,
NULL,
NULL
);
DefineCustomBoolVariable(
"multimaster.monotonic_sequences",
"Enforce monotonic behaviour of sequence values obtained from different nodes",
NULL,
&MtmMonotonicSequences,
false,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
/* XXX */
DefineCustomBoolVariable(
"multimaster.ignore_tables_without_pk",
"Do not replicate tables without primary key",
NULL,
&MtmIgnoreTablesWithoutPk,
false,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
DefineCustomStringVariable(
"multimaster.referee_connstring",
"Referee connection string",
NULL,
&MtmRefereeConnStr,
"",
PGC_POSTMASTER,
0,
NULL,
NULL,
NULL
);
DefineCustomBoolVariable(
"multimaster.volkswagen_mode",
"Pretend to be normal postgres. This means skip some NOTICE's and use local sequences. Default false.",
NULL,
&MtmVolksWagenMode,
false,
PGC_BACKEND,
GUC_NO_SHOW_ALL,
NULL,
NULL,
NULL
);
DefineCustomIntVariable(
"multimaster.max_workers",
"Maximal number of multimaster dynamic executor workers",
NULL,
&MtmMaxWorkers,
100,
0,
INT_MAX,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
DefineCustomStringVariable(
"multimaster.remote_functions",
"List of function names which should be executed remotely at all multimaster nodes instead of executing them at master and replicating result of their work",
NULL,
&MtmRemoteFunctionsList,
"lo_creat,lo_create,lo_unlink,lo_open,loread,lowrite,lo_lseek,lo_tell,lo_close,lo_export"
"pathman.create_single_range_partition,pathman.drop_partitions,pathman.create_hash_partitions,pathman.create_range_partitions,pathman.split_range_partition,pathman.drop_range_partition,pathman.add_range_partition,pathman.attach_range_partition,pathman.detach_range_partition,pathman.prepend_range_partition,pathman.append_range_partition,pathman.set_auto,pathman.set_enable_parent,pathman.merge_range_partitions,pathman.add_to_pathman_config,pathman.set_spawn_using_bgw,pathman.set_init_callback,pathman.set_interval,pathman.partition_table_concurrently,"
"public.create_single_range_partition,public.drop_partitions,public.create_hash_partitions,public.create_range_partitions,public.split_range_partition,public.drop_range_partition,public.add_range_partition,public.attach_range_partition,public.detach_range_partition,public.prepend_range_partition,public.append_range_partition,public.set_auto,public.set_enable_parent,public.merge_range_partitions,public.add_to_pathman_config,public.set_spawn_using_bgw,public.set_init_callback,public.set_interval,public.partition_table_concurrently"
,
PGC_USERSET, /* context */
GUC_LIST_INPUT, /* flags */
NULL, /* GucStringCheckHook check_hook */
MtmSetRemoteFunction, /* GucStringAssignHook
* assign_hook */
NULL /* GucShowHook show_hook */
);
DefineCustomBoolVariable(
"multimaster.break_connection",
"Break connection with client when node is no online",
NULL,
&MtmBreakConnection,
false,
PGC_BACKEND,
0,
NULL,
NULL,
NULL
);
DefineCustomBoolVariable(
"multimaster.wait_peer_commits",
"Wait until peers confirm commit of the transaction before the command returns a \"success\" to the client.",
NULL,
&MtmWaitPeerCommits,
true,
PGC_USERSET,
0,
NULL,
NULL,
NULL);
DefineCustomBoolVariable("multimaster.no_3pc",
"Don't perform 3pc for current xact. Mostly for internal usage, you should really know what you are doing.",
NULL,
&MtmNo3PC,
false,
PGC_USERSET,
/* construct a few obstacles preventing broad usage */
GUC_NO_SHOW_ALL | GUC_DISALLOW_IN_FILE,
NULL,
NULL,
NULL
);
DefineCustomIntVariable(
"multimaster.syncpoint_interval",
"Size of generated WAL between syncpoints",
NULL,
&MtmSyncpointInterval,
10*1024, /* 10 MB */
0,
INT_MAX,
PGC_SIGHUP,
GUC_UNIT_KB,
NULL,
NULL,
NULL
);
DefineCustomBoolVariable(
"multimaster.binary_basetypes",
"Send native PG types in binary format",
NULL,
&MtmBinaryBasetypes,
true,
PGC_POSTMASTER,
0,
NULL,
NULL,
NULL
);
for (i = 0; mtm_log_gucs[i].name; i++)
{
MtmLogGuc *guc = &mtm_log_gucs[i];
char *full_name;
char *desc;
MemoryContext oldcontext;
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
full_name = psprintf("multimaster.%s_log_level", guc->name);
desc = psprintf("log level for %s multimaster messages", guc->name);
MemoryContextSwitchTo(oldcontext);
DefineCustomEnumVariable(
full_name,
desc,
NULL,
&guc->val,
guc->default_val,
server_message_level_options,
PGC_SUSET,
0,
NULL,
NULL,
NULL);
}
/*
* Request additional shared resources. (These are no-ops if we're not in
* the postmaster process.) We'll allocate or attach to the shared
* resources in mtm_shmem_startup().
*/
RequestAddinShmemSpace(MTM_SHMEM_SIZE + sizeof(MtmTime));
RequestNamedLWLockTranche(MULTIMASTER_NAME, 2);
dmq_init(MtmHeartbeatSendTimeout, MtmConnectTimeout);
dmq_receiver_start_hook = MtmOnDmqReceiverConnect;
dmq_receiver_heartbeat_hook = MtmOnDmqReceiverHeartbeat;
dmq_receiver_stop_hook = MtmOnDmqReceiverDisconnect;
dmq_sender_connect_hook = MtmOnDmqSenderConnect;
dmq_sender_heartbeat_hook = MtmOnDmqSenderHeartbeat;
dmq_sender_disconnect_hook = MtmOnDmqSenderDisconnect;
MtmDDLReplicationInit();
launcher_init();
MtmStateInit();
MtmGlobalTxInit();
/*
* Install hooks.
*/
PreviousShmemStartupHook = shmem_startup_hook;
shmem_startup_hook = MtmShmemStartup;
DetectGlobalDeadLock = MtmDetectGlobalDeadLock;
#ifdef PGPRO_EE
SuspendTransactionHook = MtmSuspendTransaction;
ResumeTransactionHook = MtmResumeTransaction;
#endif
}
/*
* Module unload callback
*
* XXX: check 'drop extension multimaster'
*/
void
_PG_fini(void)
{
shmem_startup_hook = PreviousShmemStartupHook;
}
/*
* Publication named 'multimaster' acts as a flag that that multimaster
* extension was created and configured, so we can hijack transactions.
* We can't hijack transactions before configuration is done because
* configuration itself is going to need some transactions that better not
* be aborted because of Mtm->status being DISABLED. Also publication
* is uniq with respect to (db_id, pub_name) so "All your base are belong
* to us" won't happen.
*/
bool
MtmIsEnabled()
{
bool enabled;
Oid dbOid;
LWLockAcquire(Mtm->lock, LW_SHARED);
enabled = Mtm->IsEnabled;
dbOid = Mtm->DatabaseId;
LWLockRelease(Mtm->lock);
/* Consistency check */
Assert((enabled && dbOid != InvalidOid) || (!enabled && dbOid == InvalidOid));
if (!enabled)
{
/*
* Do not block another processes during possible long-time database
* transaction and do not need to catch an error for release the lock.
*/
enabled = OidIsValid(get_publication_oid(MULTIMASTER_NAME, true));
if (enabled)
{
Assert(MyDatabaseId != InvalidOid);
LWLockAcquire(Mtm->lock, LW_EXCLUSIVE);
Mtm->IsEnabled = true;
Mtm->DatabaseId = MyDatabaseId;
LWLockRelease(Mtm->lock);
}
}
else if (dbOid != MyDatabaseId)
return false;
return enabled;
}
/* XXX: delete that */
bool
MtmAllApplyWorkersFinished()
{
int i;
for (i = 0; i < MTM_MAX_NODES; i++)
{
volatile int ntasks;
LWLockAcquire(&Mtm->pools[i].lock, LW_SHARED);
if (Mtm->pools[i].nWorkers <= 0 || i == Mtm->my_node_id - 1)
{
LWLockRelease(&Mtm->pools[i].lock);
continue;
}
LWLockAcquire(&Mtm->pools[i].txlist.lock, LW_SHARED);
ntasks = Mtm->pools[i].txlist.nelems;
LWLockRelease(&Mtm->pools[i].txlist.lock);
LWLockRelease(&Mtm->pools[i].lock);
mtm_log(MtmApplyBgwFinish, "MtmAllApplyWorkersFinished %d tasks not finished from node %d",
ntasks, i+1);
if (ntasks != 0)
return false;
}
return true;
}
/*****************************************************************************
*
* Node management stuff.
*
*****************************************************************************/
/*
* Check correctness of multimaster configuration
*/
static bool
check_config(int node_id, int n_nodes)
{
bool ok = true;
int workers_required;
if (max_prepared_xacts < 1)
{
mtm_log(WARNING,
"multimaster requires max_prepared_transactions > 0, "
"because all transactions are implicitly two-phase");
ok = false;
}
if (node_id <= 0 || node_id > MTM_MAX_NODES)
{
mtm_log(WARNING,
"node_id should be in range from 1 to %d, but %d is given",
MTM_MAX_NODES, node_id);
ok = false;
}
/*
* There are 5 constant bgws (launcher + monitor, resolver, campaigner,
* replier) and, for (n - 1) neighbours 1 main receiver + up to MtmMaxWorkers
* dynamic workers. Setting max_worker_processes too low might lead to one
* receiver hogging the covers and occupying all slots with its workers
* while another one wouldn't be able to spin even one, thus hanging the
* cluster.
*/
workers_required = 5 + (n_nodes - 1) * (MtmMaxWorkers + 1);
if (max_worker_processes < workers_required)
{
mtm_log(WARNING,
"multimaster requires max_worker_processes at least "
"5 + (num_nodes - 1) * (multimaster.max_workers + 1), "
"which is %d in your configuration, but it is set to %d",
workers_required, max_worker_processes);
ok = false;
}
if (wal_level != WAL_LEVEL_LOGICAL)
{
mtm_log(WARNING,
"multimaster requires wal_level = 'logical', "
"because it is build on top of logical replication");
ok = false;
}
if (max_wal_senders < node_id)
{
mtm_log(WARNING,
"multimaster requires max_wal_senders >= %d (multimaster.max_nodes), ",
node_id);
ok = false;
}
if (max_replication_slots < node_id)
{
mtm_log(WARNING,
"multimaster requires max_replication_slots >= %d (multimaster.max_nodes), ",
node_id);
ok = false;
}
return ok;
}
/* XXX: check also that nodes are different? */
/* XXX: add connection check to after create triggers? */
Datum
mtm_init_cluster(PG_FUNCTION_ARGS)
{
char *my_conninfo = text_to_cstring(PG_GETARG_TEXT_P(0));
ArrayType *peers_arr = PG_GETARG_ARRAYTYPE_P(1);
Datum *peers_datums;
bool *peers_nulls;
int i,
rc,
n_peers;
int n_nodes;
PGconn **peer_conns;
StringInfoData local_query;
StringInfoData node_ids_arr;
/* parse array with peer connstrings */
Assert(ARR_ELEMTYPE(peers_arr) == TEXTOID);
Assert(ARR_NDIM(peers_arr) == 1);
deconstruct_array(peers_arr,
TEXTOID, -1, false, 'i',
&peers_datums, &peers_nulls, &n_peers);
n_nodes = n_peers + 1;
if (n_peers + 1 >= MTM_MAX_NODES)
mtm_log(ERROR,
"multimaster allows at maximum %d nodes, but %d was given",
MTM_MAX_NODES, n_peers + 1);
if (n_peers < 1)
mtm_log(ERROR, "at least one peer node should be specified");
/* initial node ids are 1..n_nodes */
initStringInfo(&node_ids_arr);
appendStringInfoString(&node_ids_arr, "'{");
for (i = 0; i < n_nodes; i++)
{
if (i != 0)
appendStringInfoString(&node_ids_arr, ", ");
appendStringInfo(&node_ids_arr, "%d", i + 1);
}
appendStringInfoString(&node_ids_arr, "}'");
peer_conns = (PGconn **) palloc0(n_peers * sizeof(PGconn *));
/* open connections to peers and create multimaster extension */
for (i = 0; i < n_peers; i++)
{
PGresult *res;
char *conninfo = TextDatumGetCString(peers_datums[i]);
StringInfoData query;
int j;
/* connect */
peer_conns[i] = PQconnectdb(conninfo);
if (PQstatus(peer_conns[i]) != CONNECTION_OK)
{
char *msg = pchomp(PQerrorMessage(peer_conns[i]));
PQfinish(peer_conns[i]);
mtm_log(ERROR,
"Could not connect to a node '%s' from this node: %s",
conninfo, msg);
}
/* create extension */
res = PQexec(peer_conns[i], "create extension if not exists multimaster");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
char *msg = pchomp(PQerrorMessage(peer_conns[i]));
PQclear(res);
PQfinish(peer_conns[i]);
mtm_log(ERROR,
"Failed to create multimaster extension on '%s': %s",
conninfo, msg);
}