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bdr_seq.c
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bdr_seq.c
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/* -------------------------------------------------------------------------
*
* bdr_seq.c
* A distributed sequence implementation.
*
* Replication???
*
* Copyright (C) 2012-2015, PostgreSQL Global Development Group
*
* IDENTIFICATION
* bdr_seq.c
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "bdr.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "access/reloptions.h"
#include "access/seqam.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "commands/sequence.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/snapmgr.h"
#include "storage/bufmgr.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "storage/sinvaladt.h"
typedef struct BdrSequencerSlot
{
Oid database_oid;
Size nnodes;
Latch *proclatch;
} BdrSequencerSlot;
typedef struct BdrSequencerControl
{
int next_slot;
BdrSequencerSlot slots[FLEXIBLE_ARRAY_MEMBER];
} BdrSequencerControl;
typedef struct BdrSequenceValues {
int64 start_value;
int64 next_value;
int64 end_value;
} BdrSequenceValues;
/* Our offset within the shared memory array of registered sequence managers */
static int seq_slot = -1;
/* cached relids */
Oid BdrSequenceValuesRelid; /* bdr_sequence_values */
Oid BdrSequenceElectionsRelid; /* bdr_sequence_elections */
Oid BdrVotesRelid; /* bdr_votes */
static BdrSequencerControl *BdrSequencerCtl = NULL;
/* how many nodes have we built shmem for */
static size_t bdr_seq_nsequencers = 0;
static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
static bool bdr_seq_pending_wakeup = false;
static relopt_kind bdr_seq_relopt_kind = RELOPT_KIND_SEQUENCE;
/* vote, the logic is in a function */
const char* vote_sql = ""
"SELECT bdr.bdr_sequencer_vote($1, $2, $3, $4);\n";
const char *start_elections_sql =
"WITH to_be_updated_sequences AS (\n"
" SELECT\n"
" pg_namespace.nspname AS seqschema,\n"
" seq.relname AS seqname,\n"
" COUNT(bdr_sequence_values) AS open_seq_chunks,\n"
" GREATEST(COALESCE((\n"
" SELECT max(upper(seqrange))\n"
" FROM bdr_sequence_values max_val\n"
" WHERE\n"
" max_val.seqschema = pg_namespace.nspname\n"
" AND max_val.seqname = seq.relname\n"
" ), 0), (SELECT start_value FROM pg_sequence_parameters(seq.oid)))\n"
" AS current_max,\n"
" seq.cache_chunks\n"
" FROM\n"
" (SELECT\n"
" pg_class.oid,\n"
" pg_class.relnamespace,\n"
" pg_class.relname,\n"
" COALESCE((SELECT split_part(o, '=', 2)::int\n"
" FROM unnest(pg_class.reloptions) o\n"
" WHERE split_part(o, '=', 1) = 'cache_chunks'), 5)\n"
" AS cache_chunks\n"
" FROM\n"
" pg_class\n"
" WHERE\n"
" pg_class.relkind = 'S' AND\n"
" pg_class.relam = (SELECT oid FROM pg_seqam WHERE seqamname = 'bdr')\n"
" ) seq\n"
" JOIN pg_namespace ON (seq.relnamespace = pg_namespace.oid)\n"
" LEFT JOIN bdr_sequence_values ON (\n"
" bdr_sequence_values.seqschema = pg_namespace.nspname\n"
" AND bdr_sequence_values.seqname = seq.relname\n"
" AND bdr_sequence_values.emptied = false\n"
" AND bdr_sequence_values.in_use = false\n"
" AND bdr_sequence_values.failed = false\n"
" AND bdr_sequence_values.owning_sysid = $1\n"
" AND bdr_sequence_values.owning_tlid = $2\n"
" AND bdr_sequence_values.owning_dboid = $3\n"
" AND bdr_sequence_values.owning_riname = $4\n"
" )\n"
" GROUP BY\n"
" seq.relname,\n"
" pg_namespace.nspname,\n"
" seq.oid,\n"
" seq.cache_chunks\n"
" HAVING\n"
" count(bdr_sequence_values) <= cache_chunks\n"
"),\n"
"to_be_inserted_chunks AS (\n"
" SELECT\n"
" seqschema,\n"
" seqname,\n"
" current_max,\n"
" generate_series(\n"
" current_max,\n"
" -- 10000 is the chunk size, -1 is to get < instead <= out of generate_series\n"
" current_max + 10000 * (cache_chunks - open_seq_chunks) - 1,\n"
" 10000) chunk_start\n"
" FROM to_be_updated_sequences\n"
" LIMIT 500\n"
"),\n"
"inserted_chunks AS (\n"
" INSERT INTO bdr_sequence_elections(\n"
" owning_sysid,\n"
" owning_tlid,\n"
" owning_dboid,\n"
" owning_riname,\n"
" owning_election_id,\n"
" vote_type,\n"
" open,\n"
" seqschema,\n"
" seqname,\n"
" seqrange\n"
" )\n"
" SELECT\n"
" $1,\n"
" $2,\n"
" $3,\n"
" $4,\n"
" (\n"
" SELECT COALESCE(max(owning_election_id), 0)\n"
" FROM bdr_sequence_elections biggest\n"
" WHERE\n"
" biggest.owning_sysid = $1\n"
" AND biggest.owning_tlid = $2\n"
" AND biggest.owning_dboid = $3\n"
" AND biggest.owning_riname = $4\n"
" ) + row_number() OVER (),\n"
" 'sequence',\n"
" true AS open,\n"
" seqschema,\n"
" seqname,\n"
" int8range(chunk_start, chunk_start + 10000) AS seqrange\n"
" FROM to_be_inserted_chunks\n"
" RETURNING\n"
" seqschema,\n"
" seqname,\n"
" seqrange\n"
")\n"
"\n"
"INSERT INTO bdr_sequence_values(\n"
" owning_sysid,\n"
" owning_tlid,\n"
" owning_dboid,\n"
" owning_riname,\n"
" seqschema,\n"
" seqname,\n"
" confirmed,\n"
" in_use,\n"
" emptied,\n"
" seqrange\n"
")\n"
"SELECT\n"
" $1,\n"
" $2,\n"
" $3,\n"
" $4,\n"
" seqschema,\n"
" seqname,\n"
" false AS confirmed,\n"
" false AS in_use,\n"
" false AS emptied,\n"
" int8range(chunk_start, chunk_start + 10000)\n"
"FROM to_be_inserted_chunks\n"
"-- force evaluation \n"
"WHERE (SELECT count(*) FROM inserted_chunks) >= 0\n"
"RETURNING\n"
" owning_sysid,\n"
" owning_tlid,\n"
" owning_dboid,\n"
" owning_riname,\n"
" seqschema,\n"
" seqname,\n"
" confirmed,\n"
" emptied,\n"
" seqrange\n"
;
const char *tally_elections_sql =
"WITH tallied_votes AS (\n"
"SELECT\n"
" election.owning_sysid,\n"
" election.owning_tlid,\n"
" election.owning_dboid,\n"
" election.owning_riname,\n"
" election.owning_election_id,\n"
" election.seqschema,\n"
" election.seqname,\n"
" election.seqrange,\n"
" SUM(COALESCE((vote.vote = true)::int, 0)) AS yays,\n"
" SUM(COALESCE((vote.vote = false)::int, 0)) AS nays,\n"
" COUNT(vote.vote) AS nr_votes,\n"
" /* majority of others */\n"
" COUNT(vote.vote) >= ceil($5/ 2.0) AS sufficient\n"
"FROM\n"
" bdr_sequence_elections election\n"
" LEFT JOIN bdr_votes vote ON (\n"
" election.owning_sysid = vote.vote_sysid\n"
" AND election.owning_tlid = vote.vote_tlid\n"
" AND election.owning_dboid = vote.vote_dboid\n"
" AND election.owning_riname = vote.vote_riname\n"
" AND election.owning_election_id = vote.vote_election_id\n"
" )\n"
"WHERE\n"
" election.open\n"
" AND election.owning_sysid = $1\n"
" AND election.owning_tlid = $2\n"
" AND election.owning_dboid = $3\n"
" AND election.owning_riname = $4\n"
"GROUP BY\n"
" election.owning_sysid,\n"
" election.owning_tlid,\n"
" election.owning_dboid,\n"
" election.owning_riname,\n"
" election.owning_election_id,\n"
" election.seqschema,\n"
" election.seqname,\n"
" election.seqrange\n"
"),\n"
"cast_votes AS (\n"
" UPDATE bdr_sequence_elections\n"
" SET\n"
" open = false,\n"
" success = (nays = 0 OR yays >= ceil($5/ 2.0))\n"
" FROM tallied_votes\n"
" WHERE\n"
" bdr_sequence_elections.owning_sysid = tallied_votes.owning_sysid\n"
" AND bdr_sequence_elections.owning_tlid = tallied_votes.owning_tlid\n"
" AND bdr_sequence_elections.owning_dboid = tallied_votes.owning_dboid\n"
" AND bdr_sequence_elections.owning_riname = tallied_votes.owning_riname\n"
" AND bdr_sequence_elections.owning_election_id = tallied_votes.owning_election_id\n"
" AND tallied_votes.sufficient\n"
" RETURNING bdr_sequence_elections.*\n"
"),\n"
"successfull_sequence_values AS (\n"
" UPDATE bdr_sequence_values\n"
" SET\n"
" confirmed = true\n"
" FROM cast_votes\n"
" WHERE\n"
" cast_votes.success = true\n"
" AND bdr_sequence_values.seqschema = cast_votes.seqschema\n"
" AND bdr_sequence_values.seqname = cast_votes.seqname\n"
" AND bdr_sequence_values.seqrange = cast_votes.seqrange\n"
" AND bdr_sequence_values.owning_sysid = $1\n"
" AND bdr_sequence_values.owning_tlid = $2\n"
" AND bdr_sequence_values.owning_dboid = $3\n"
" AND bdr_sequence_values.owning_riname = $4\n"
" RETURNING bdr_sequence_values.*\n"
"),\n"
"failed_sequence_values AS (\n"
" UPDATE bdr_sequence_values\n"
" SET\n"
" failed = true\n"
" FROM cast_votes\n"
" WHERE\n"
" cast_votes.success = false\n"
" AND bdr_sequence_values.seqschema = cast_votes.seqschema\n"
" AND bdr_sequence_values.seqname = cast_votes.seqname\n"
" AND bdr_sequence_values.seqrange = cast_votes.seqrange\n"
" AND bdr_sequence_values.owning_sysid = $1\n"
" AND bdr_sequence_values.owning_tlid = $2\n"
" AND bdr_sequence_values.owning_dboid = $3\n"
" AND bdr_sequence_values.owning_riname = $4\n"
" RETURNING bdr_sequence_values.*\n"
")\n"
"\n"
"SELECT\n"
" seqschema,\n"
" seqname,\n"
" seqrange,\n"
" 'success'::text\n"
"FROM successfull_sequence_values\n"
"\n"
"UNION ALL\n"
"\n"
"SELECT\n"
" seqschema,\n"
" seqname,\n"
" seqrange,\n"
" 'failed'::text\n"
"FROM failed_sequence_values\n"
"\n"
"UNION ALL\n"
"\n"
"SELECT\n"
" seqschema,\n"
" seqname,\n"
" seqrange,\n"
" 'pending'::text\n"
"FROM tallied_votes\n"
"WHERE NOT sufficient\n"
;
const char *fill_sequences_sql =
"SELECT\n"
" pg_class.oid seqoid,\n"
" pg_namespace.nspname seqschema,\n"
" pg_class.relname seqname\n"
"FROM pg_class\n"
" JOIN pg_seqam ON (pg_seqam.oid = pg_class.relam)\n"
" JOIN pg_namespace ON (pg_class.relnamespace = pg_namespace.oid)\n"
"WHERE\n"
" relkind = 'S'\n"
" AND seqamname = 'bdr'\n"
"ORDER BY pg_class.oid\n"
;
const char *get_chunk_sql =
"UPDATE bdr_sequence_values\n"
" SET in_use = true\n"
"WHERE\n"
" (\n"
" owning_sysid,\n"
" owning_tlid,\n"
" owning_dboid,\n"
" owning_riname,\n"
" seqname,\n"
" seqschema,\n"
" seqrange\n"
" )\n"
" =\n"
" (\n"
" SELECT\n"
" newval.owning_sysid,\n"
" newval.owning_tlid,\n"
" newval.owning_dboid,\n"
" newval.owning_riname,\n"
" newval.seqname,\n"
" newval.seqschema,\n"
" newval.seqrange\n"
" FROM bdr_sequence_values newval\n"
" WHERE\n"
" newval.confirmed\n"
" AND NOT newval.emptied\n"
" AND NOT newval.in_use\n"
" AND newval.owning_sysid = $1\n"
" AND newval.owning_tlid = $2\n"
" AND newval.owning_dboid = $3\n"
" AND newval.owning_riname = $4\n"
" AND newval.seqschema = $5\n"
" AND newval.seqname = $6\n"
" ORDER BY newval.seqrange ASC\n"
" LIMIT 1\n"
" FOR UPDATE\n"
" )\n"
"RETURNING\n"
" lower(seqrange),\n"
" upper(seqrange)\n"
;
static Size
bdr_sequencer_shmem_size(void)
{
Size size = 0;
size = add_size(size, sizeof(BdrSequencerControl));
size = add_size(size, mul_size(bdr_seq_nsequencers, sizeof(BdrSequencerSlot)));
return size;
}
static void
bdr_sequencer_shmem_shutdown(int code, Datum arg)
{
BdrSequencerSlot *slot;
if (seq_slot < 0)
return;
Assert(seq_slot < bdr_seq_nsequencers);
slot = &BdrSequencerCtl->slots[seq_slot];
slot->database_oid = InvalidOid;
slot->proclatch = NULL;
seq_slot = -1;
}
static void
bdr_sequencer_shmem_startup(void)
{
bool found;
if (prev_shmem_startup_hook != NULL)
prev_shmem_startup_hook();
LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
BdrSequencerCtl = ShmemInitStruct("bdr_sequencer",
bdr_sequencer_shmem_size(),
&found);
if (!found)
{
/* initialize */
memset(BdrSequencerCtl, 0, bdr_sequencer_shmem_size());
/*
* next_slot allows perdb workers to allocate seq slots.
* The sequencer will likely be separated into a different
* worker later.
*/
BdrSequencerCtl->next_slot = 0;
}
LWLockRelease(AddinShmemInitLock);
on_shmem_exit(bdr_sequencer_shmem_shutdown, (Datum) 0);
}
void
bdr_sequencer_shmem_init(int sequencers)
{
Assert(process_shared_preload_libraries_in_progress);
bdr_seq_nsequencers = sequencers;
RequestAddinShmemSpace(bdr_sequencer_shmem_size());
prev_shmem_startup_hook = shmem_startup_hook;
shmem_startup_hook = bdr_sequencer_shmem_startup;
/*
* We do the reloptions initialization here because this function is called
* at startup for every backend.
*/
bdr_seq_relopt_kind = add_reloption_kind();
add_int_reloption(bdr_seq_relopt_kind, "cache_chunks",
"Sets how many chunks shoult be cached on each node.",
5, 5, 100);
}
/*
* The perdb worker doing sequencer setup needs to know what slot to
* allocate for the next sequencer.
*
* This should go away once the sequencer is separated into its own
* worker.
*/
int
bdr_sequencer_get_next_free_slot(void)
{
return BdrSequencerCtl->next_slot ++;
}
void
bdr_sequencer_wakeup(void)
{
size_t off;
BdrSequencerSlot *slot;
for (off = 0; off < bdr_seq_nsequencers; off++)
{
slot = &BdrSequencerCtl->slots[off];
/* FIXME: locking! */
if (slot->database_oid == InvalidOid)
continue;
if (slot->database_oid != MyDatabaseId)
continue;
SetLatch(slot->proclatch);
}
}
static void
bdr_sequence_xact_callback(XactEvent event, void *arg)
{
if (event != XACT_EVENT_COMMIT)
return;
if (bdr_seq_pending_wakeup)
{
bdr_sequencer_wakeup();
bdr_seq_pending_wakeup = false;
}
}
/*
* Schedule a wakeup of all sequencer workers, as soon as this transaction
* commits.
*
* This is e.g. useful when a new sequnece is created, and the voting process
* should start immediately.
*
* NB: There's a window between the commit and this callback in which this
* backend could die without causing a cluster wide restart. So we need to
* periodically check whether we've missed wakeups.
*/
void
bdr_schedule_eoxact_sequencer_wakeup(void)
{
static bool registered = false;
if (!registered)
{
RegisterXactCallback(bdr_sequence_xact_callback, NULL);
registered = true;
}
bdr_seq_pending_wakeup = true;
}
void
bdr_sequencer_set_nnodes(Size nnodes)
{
BdrSequencerSlot *slot = &BdrSequencerCtl->slots[seq_slot];
slot->nnodes = nnodes;
}
void
bdr_sequencer_init(int new_seq_slot, Size nnodes)
{
BdrSequencerSlot *slot;
Assert(seq_slot == -1);
seq_slot = new_seq_slot;
slot = &BdrSequencerCtl->slots[seq_slot];
slot->database_oid = MyDatabaseId;
slot->proclatch = &MyProc->procLatch;
slot->nnodes = nnodes;
}
/*
* Acquire sequencer lock.
*
* We lock on on our seqam instead of the underlying relations. That's
* advantageous because we only want to prevent modifications by the sequencer
* or apply processes, it's perfectly fine for auto-analyze/vacuum to process
* the relation.
*/
void
bdr_sequencer_lock(void)
{
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, "acquiring sequencer lock");
LockDatabaseObject(SeqAccessMethodRelationId, BdrSeqamOid, InvalidOid,
ExclusiveLock);
}
bool
bdr_sequencer_vote(void)
{
static SPIPlanPtr plan;
Oid argtypes[4];
Datum values[4];
char nulls[4];
char local_sysid[32];
int ret;
int processed = 0;
snprintf(local_sysid, sizeof(local_sysid), UINT64_FORMAT,
GetSystemIdentifier());
argtypes[0] = TEXTOID;
nulls[0] = false;
values[0] = CStringGetTextDatum(local_sysid);
argtypes[1] = OIDOID;
nulls[1] = false;
values[1] = ObjectIdGetDatum(ThisTimeLineID);
argtypes[2] = OIDOID;
values[2] = ObjectIdGetDatum(MyDatabaseId);
nulls[2] = false;
argtypes[3] = TEXTOID;
values[3] = CStringGetTextDatum("");
nulls[3] = false;
StartTransactionCommand();
SPI_connect();
bdr_sequencer_lock();
PushActiveSnapshot(GetTransactionSnapshot());
if (plan == NULL)
{
plan = SPI_prepare(vote_sql, 4, argtypes);
SPI_keepplan(plan);
}
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, "sequence voting");
ret = SPI_execute_plan(plan, values, nulls, false, 0);
if (ret != SPI_OK_SELECT)
elog(ERROR, "expected SPI state %u, got %u", SPI_OK_INSERT, ret);
if (SPI_processed > 0)
{
HeapTuple tuple = SPI_tuptable->vals[0];
TupleDesc tupdesc = SPI_tuptable->tupdesc;
Datum inserted;
bool isnull;
inserted = SPI_getbinval(tuple, tupdesc, 1, &isnull);
Assert(!isnull);
processed = DatumGetInt32(inserted);
}
PopActiveSnapshot();
SPI_finish();
CommitTransactionCommand();
pgstat_report_stat(false);
elog(DEBUG1, "started %d votes", processed);
return processed > 0;
}
/*
* Check whether we need to initiate a voting procedure for getting new
* sequence chunks.
*/
bool
bdr_sequencer_start_elections(void)
{
static SPIPlanPtr plan;
Oid argtypes[4];
Datum values[4];
char nulls[4];
char local_sysid[32];
int ret;
int processed;
snprintf(local_sysid, sizeof(local_sysid), UINT64_FORMAT,
GetSystemIdentifier());
StartTransactionCommand();
SPI_connect();
argtypes[0] = TEXTOID;
nulls[0] = false;
values[0] = CStringGetTextDatum(local_sysid);
argtypes[1] = OIDOID;
nulls[1] = false;
values[1] = ObjectIdGetDatum(ThisTimeLineID);
argtypes[2] = OIDOID;
values[2] = ObjectIdGetDatum(MyDatabaseId);
nulls[2] = false;
argtypes[3] = TEXTOID;
values[3] = CStringGetTextDatum("");
nulls[3] = false;
bdr_sequencer_lock();
PushActiveSnapshot(GetTransactionSnapshot());
if (plan == NULL)
{
plan = SPI_prepare(start_elections_sql, 4, argtypes);
SPI_keepplan(plan);
}
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, "start_elections");
ret = SPI_execute_plan(plan, values, nulls, false, 0);
if (ret != SPI_OK_INSERT_RETURNING)
elog(ERROR, "expected SPI state %u, got %u", SPI_OK_INSERT_RETURNING, ret);
elog(DEBUG1, "started %d elections", SPI_processed);
processed = SPI_processed;
PopActiveSnapshot();
SPI_finish();
CommitTransactionCommand();
pgstat_report_stat(false);
return processed > 0;
}
/*
* Check whether enough votes have come in for any of *our* in progress
* elections.
*/
void
bdr_sequencer_tally(void)
{
static SPIPlanPtr plan;
Oid argtypes[5];
Datum values[5];
char nulls[5];
char local_sysid[32];
int ret;
snprintf(local_sysid, sizeof(local_sysid), UINT64_FORMAT,
GetSystemIdentifier());
StartTransactionCommand();
SPI_connect();
argtypes[0] = TEXTOID;
nulls[0] = false;
values[0] = CStringGetTextDatum(local_sysid);
argtypes[1] = OIDOID;
nulls[1] = false;
values[1] = ObjectIdGetDatum(ThisTimeLineID);
argtypes[2] = OIDOID;
values[2] = ObjectIdGetDatum(MyDatabaseId);
nulls[2] = false;
argtypes[3] = TEXTOID;
values[3] = CStringGetTextDatum("");
nulls[3] = false;
argtypes[4] = INT4OID;
values[4] = Int32GetDatum(BdrSequencerCtl->slots[seq_slot].nnodes);
nulls[4] = false;
bdr_sequencer_lock();
PushActiveSnapshot(GetTransactionSnapshot());
if (plan == NULL)
{
plan = SPI_prepare(tally_elections_sql, 5, argtypes);
SPI_keepplan(plan);
}
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, "tally_elections");
ret = SPI_execute_plan(plan, values, nulls, false, 0);
if (ret != SPI_OK_SELECT)
elog(ERROR, "expected SPI state %u, got %u", SPI_OK_SELECT, ret);
elog(DEBUG1, "tallied %d elections", SPI_processed);
PopActiveSnapshot();
SPI_finish();
CommitTransactionCommand();
pgstat_report_stat(false);
}
static int
bdr_sequence_value_cmp(const void *a, const void *b)
{
const BdrSequenceValues *left = a;
const BdrSequenceValues *right = b;
if (left->start_value < right->start_value)
return -1;
if (left->start_value == right->start_value)
return 0;
return 1;
}
/*
* Replace a single (uninitialized or used up) chunk by a free one. Mark the
* new chunk from bdr_sequence_values as in_use.
*
* Returns whether we could find a chunk or not.
*/
static bool
bdr_sequencer_fill_chunk(Oid seqoid, char *seqschema, char *seqname,
BdrSequenceValues *curval)
{
static SPIPlanPtr plan;
Oid argtypes[6];
Datum values[6];
char nulls[6];
char local_sysid[32];
int ret;
int64 lower, upper;
bool success;
SPI_push();
SPI_connect();
snprintf(local_sysid, sizeof(local_sysid), UINT64_FORMAT,
GetSystemIdentifier());
argtypes[0] = TEXTOID;
nulls[0] = false;
values[0] = CStringGetTextDatum(local_sysid);
argtypes[1] = OIDOID;
nulls[1] = false;
values[1] = ObjectIdGetDatum(ThisTimeLineID);
argtypes[2] = OIDOID;
values[2] = ObjectIdGetDatum(MyDatabaseId);
nulls[2] = false;
argtypes[3] = TEXTOID;
values[3] = CStringGetTextDatum("");
nulls[3] = false;
argtypes[4] = TEXTOID;
values[4] = CStringGetTextDatum(seqschema);
nulls[4] = false;
argtypes[5] = TEXTOID;
values[5] = CStringGetTextDatum(seqname);
nulls[5] = false;
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, "get_chunk");
if (plan == NULL)
{
plan = SPI_prepare(get_chunk_sql, 6, argtypes);
SPI_keepplan(plan);
}
ret = SPI_execute_plan(plan, values, nulls, false, 0);
if (ret != SPI_OK_UPDATE_RETURNING)
elog(ERROR, "expected SPI state %u, got %u", SPI_OK_UPDATE_RETURNING, ret);
if (SPI_processed != 1)
{
elog(DEBUG2, "no free chunks for sequence %s.%s",
seqschema, seqname);
success = false;
}
else
{
HeapTuple tup = SPI_tuptable->vals[0];
bool isnull;
lower = DatumGetInt64(SPI_getbinval(tup, SPI_tuptable->tupdesc, 1, &isnull));
Assert(!isnull);
upper = DatumGetInt64(SPI_getbinval(tup, SPI_tuptable->tupdesc, 2, &isnull));
Assert(!isnull);
elog(DEBUG2, "got chunk [%zu, %zu) for sequence %s.%s",
lower, upper, seqschema, seqname);
curval->start_value = lower;
curval->next_value = lower;
curval->end_value = upper;
success = true;
}
SPI_finish();
SPI_pop();
return success;
}
/*
* Search for used up chunks in one bdr sequence.
*/
static void
bdr_sequencer_fill_sequence(Oid seqoid, char *seqschema, char *seqname)
{
Buffer buf;
SeqTable elm;
Relation rel;
HeapTupleData seqtuple;
Datum values[SEQ_COL_LASTCOL];
bool nulls[SEQ_COL_LASTCOL];
HeapTuple newtup;
Page page, temppage;
BdrSequenceValues *curval, *firstval;
int i;
bool acquired_new = false;
LockRelId heaprelid;
LOCKTAG heaplocktag;
VirtualTransactionId *lockholders;
/* lock page, fill heaptup */
init_sequence(seqoid, &elm, &rel);
(void) read_seq_tuple(elm, rel, &buf, &seqtuple);
/* get values */
heap_deform_tuple(&seqtuple, RelationGetDescr(rel),
values, nulls);
/* now make sure we have space for our own data */
if (nulls[SEQ_COL_AMDATA - 1])
{
struct varlena *vl = palloc0(VARHDRSZ + sizeof(BdrSequenceValues) * 10);
SET_VARSIZE(vl, VARHDRSZ + sizeof(BdrSequenceValues) * 10);
nulls[SEQ_COL_AMDATA - 1] = false;
values[SEQ_COL_AMDATA - 1] = PointerGetDatum(vl);
}
firstval = (BdrSequenceValues *)
VARDATA_ANY(DatumGetByteaP(values[SEQ_COL_AMDATA - 1]));
curval = firstval;
for (i = 0; i < 10; i ++)
{
if (curval->next_value == curval->end_value)
{
if (curval->end_value > 0)
elog(DEBUG1, "sequence %s.%s: used up old chunk",
seqschema, seqname);
elog(DEBUG2, "sequence %s.%s: needs new batch %i",
seqschema, seqname, i);
if (bdr_sequencer_fill_chunk(seqoid, seqschema, seqname, curval))
acquired_new = true;
else
break;
}
curval++;
}
if (!acquired_new)
goto done_with_sequence;
/* sort chunks, so we always use the smallest one first */
qsort(firstval, 10, sizeof(BdrSequenceValues), bdr_sequence_value_cmp);
newtup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
/* special requirements for sequence tuples */
HeapTupleHeaderSetXmin(newtup->t_data, FrozenTransactionId);
HeapTupleHeaderSetXminFrozen(newtup->t_data);
HeapTupleHeaderSetCmin(newtup->t_data, FirstCommandId);
HeapTupleHeaderSetXmax(newtup->t_data, InvalidTransactionId);
newtup->t_data->t_infomask |= HEAP_XMAX_INVALID;
ItemPointerSet(&newtup->t_data->t_ctid, 0, FirstOffsetNumber);
page = BufferGetPage(buf);
temppage = PageGetTempPage(page);
/* replace page contents, the direct way */
PageInit(temppage, BufferGetPageSize(buf), PageGetSpecialSize(page));
memcpy(PageGetSpecialPointer(temppage),
PageGetSpecialPointer(page),
PageGetSpecialSize(page));
if (PageAddItem(temppage, (Item) newtup->t_data, newtup->t_len,
FirstOffsetNumber, false, false) == InvalidOffsetNumber)
elog(PANIC, "fill_sequence: failed to add item to page");
PageSetLSN(temppage, PageGetLSN(page));
START_CRIT_SECTION();
MarkBufferDirty(buf);
memcpy(page, temppage, BufferGetPageSize(buf));
seqtuple.t_len = newtup->t_len;
log_sequence_tuple(rel, &seqtuple, page);
END_CRIT_SECTION();
done_with_sequence: