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pgrowlocks.c
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1 /*
2  * contrib/pgrowlocks/pgrowlocks.c
3  *
4  * Copyright (c) 2005-2006 Tatsuo Ishii
5  *
6  * Permission to use, copy, modify, and distribute this software and
7  * its documentation for any purpose, without fee, and without a
8  * written agreement is hereby granted, provided that the above
9  * copyright notice and this paragraph and the following two
10  * paragraphs appear in all copies.
11  *
12  * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
13  * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
14  * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
15  * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
16  * OF THE POSSIBILITY OF SUCH DAMAGE.
17  *
18  * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20  * A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
21  * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
22  * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23  */
24 
25 #include "postgres.h"
26 
27 #include "access/multixact.h"
28 #include "access/relscan.h"
29 #include "access/xact.h"
30 #include "catalog/namespace.h"
31 #include "catalog/pg_authid.h"
32 #include "funcapi.h"
33 #include "miscadmin.h"
34 #include "storage/bufmgr.h"
35 #include "storage/procarray.h"
36 #include "utils/acl.h"
37 #include "utils/builtins.h"
38 #include "utils/rel.h"
39 #include "utils/snapmgr.h"
40 #include "utils/tqual.h"
41 #include "utils/varlena.h"
42 
44 
46 
47 /* ----------
48  * pgrowlocks:
49  * returns tids of rows being locked
50  * ----------
51  */
52 
53 #define NCHARS 32
54 
55 typedef struct
56 {
59  int ncolumns;
60 } MyData;
61 
62 #define Atnum_tid 0
63 #define Atnum_xmax 1
64 #define Atnum_ismulti 2
65 #define Atnum_xids 3
66 #define Atnum_modes 4
67 #define Atnum_pids 5
68 
69 Datum
71 {
72  FuncCallContext *funcctx;
73  HeapScanDesc scan;
74  HeapTuple tuple;
75  TupleDesc tupdesc;
76  AttInMetadata *attinmeta;
77  Datum result;
78  MyData *mydata;
79  Relation rel;
80 
81  if (SRF_IS_FIRSTCALL())
82  {
83  text *relname;
84  RangeVar *relrv;
85  MemoryContext oldcontext;
86  AclResult aclresult;
87 
88  funcctx = SRF_FIRSTCALL_INIT();
89  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
90 
91  /* Build a tuple descriptor for our result type */
92  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
93  elog(ERROR, "return type must be a row type");
94 
95  attinmeta = TupleDescGetAttInMetadata(tupdesc);
96  funcctx->attinmeta = attinmeta;
97 
98  relname = PG_GETARG_TEXT_PP(0);
100  rel = heap_openrv(relrv, AccessShareLock);
101 
102  /*
103  * check permissions: must have SELECT on table or be in
104  * pg_stat_scan_tables
105  */
106  aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
107  ACL_SELECT);
108  if (aclresult != ACLCHECK_OK)
110 
111  if (aclresult != ACLCHECK_OK)
112  aclcheck_error(aclresult, ACL_KIND_CLASS,
114 
115  scan = heap_beginscan(rel, GetActiveSnapshot(), 0, NULL);
116  mydata = palloc(sizeof(*mydata));
117  mydata->rel = rel;
118  mydata->scan = scan;
119  mydata->ncolumns = tupdesc->natts;
120  funcctx->user_fctx = mydata;
121 
122  MemoryContextSwitchTo(oldcontext);
123  }
124 
125  funcctx = SRF_PERCALL_SETUP();
126  attinmeta = funcctx->attinmeta;
127  mydata = (MyData *) funcctx->user_fctx;
128  scan = mydata->scan;
129 
130  /* scan the relation */
131  while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
132  {
133  HTSU_Result htsu;
134  TransactionId xmax;
135  uint16 infomask;
136 
137  /* must hold a buffer lock to call HeapTupleSatisfiesUpdate */
139 
140  htsu = HeapTupleSatisfiesUpdate(tuple,
141  GetCurrentCommandId(false),
142  scan->rs_cbuf);
143  xmax = HeapTupleHeaderGetRawXmax(tuple->t_data);
144  infomask = tuple->t_data->t_infomask;
145 
146  /*
147  * A tuple is locked if HTSU returns BeingUpdated.
148  */
149  if (htsu == HeapTupleBeingUpdated)
150  {
151  char **values;
152 
153  values = (char **) palloc(mydata->ncolumns * sizeof(char *));
154 
155  values[Atnum_tid] = (char *) DirectFunctionCall1(tidout,
156  PointerGetDatum(&tuple->t_self));
157 
158  values[Atnum_xmax] = palloc(NCHARS * sizeof(char));
159  snprintf(values[Atnum_xmax], NCHARS, "%d", xmax);
160  if (infomask & HEAP_XMAX_IS_MULTI)
161  {
162  MultiXactMember *members;
163  int nmembers;
164  bool first = true;
165  bool allow_old;
166 
167  values[Atnum_ismulti] = pstrdup("true");
168 
169  allow_old = HEAP_LOCKED_UPGRADED(infomask);
170  nmembers = GetMultiXactIdMembers(xmax, &members, allow_old,
171  false);
172  if (nmembers == -1)
173  {
174  values[Atnum_xids] = "{0}";
175  values[Atnum_modes] = "{transient upgrade status}";
176  values[Atnum_pids] = "{0}";
177  }
178  else
179  {
180  int j;
181 
182  values[Atnum_xids] = palloc(NCHARS * nmembers);
183  values[Atnum_modes] = palloc(NCHARS * nmembers);
184  values[Atnum_pids] = palloc(NCHARS * nmembers);
185 
186  strcpy(values[Atnum_xids], "{");
187  strcpy(values[Atnum_modes], "{");
188  strcpy(values[Atnum_pids], "{");
189 
190  for (j = 0; j < nmembers; j++)
191  {
192  char buf[NCHARS];
193 
194  if (!first)
195  {
196  strcat(values[Atnum_xids], ",");
197  strcat(values[Atnum_modes], ",");
198  strcat(values[Atnum_pids], ",");
199  }
200  snprintf(buf, NCHARS, "%d", members[j].xid);
201  strcat(values[Atnum_xids], buf);
202  switch (members[j].status)
203  {
205  snprintf(buf, NCHARS, "Update");
206  break;
208  snprintf(buf, NCHARS, "No Key Update");
209  break;
211  snprintf(buf, NCHARS, "For Update");
212  break;
214  snprintf(buf, NCHARS, "For No Key Update");
215  break;
217  snprintf(buf, NCHARS, "Share");
218  break;
220  snprintf(buf, NCHARS, "Key Share");
221  break;
222  }
223  strcat(values[Atnum_modes], buf);
224  snprintf(buf, NCHARS, "%d",
225  BackendXidGetPid(members[j].xid));
226  strcat(values[Atnum_pids], buf);
227 
228  first = false;
229  }
230 
231  strcat(values[Atnum_xids], "}");
232  strcat(values[Atnum_modes], "}");
233  strcat(values[Atnum_pids], "}");
234  }
235  }
236  else
237  {
238  values[Atnum_ismulti] = pstrdup("false");
239 
240  values[Atnum_xids] = palloc(NCHARS * sizeof(char));
241  snprintf(values[Atnum_xids], NCHARS, "{%d}", xmax);
242 
243  values[Atnum_modes] = palloc(NCHARS);
244  if (infomask & HEAP_XMAX_LOCK_ONLY)
245  {
246  if (HEAP_XMAX_IS_SHR_LOCKED(infomask))
247  snprintf(values[Atnum_modes], NCHARS, "{For Share}");
248  else if (HEAP_XMAX_IS_KEYSHR_LOCKED(infomask))
249  snprintf(values[Atnum_modes], NCHARS, "{For Key Share}");
250  else if (HEAP_XMAX_IS_EXCL_LOCKED(infomask))
251  {
252  if (tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED)
253  snprintf(values[Atnum_modes], NCHARS, "{For Update}");
254  else
255  snprintf(values[Atnum_modes], NCHARS, "{For No Key Update}");
256  }
257  else
258  /* neither keyshare nor exclusive bit it set */
259  snprintf(values[Atnum_modes], NCHARS,
260  "{transient upgrade status}");
261  }
262  else
263  {
264  if (tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED)
265  snprintf(values[Atnum_modes], NCHARS, "{Update}");
266  else
267  snprintf(values[Atnum_modes], NCHARS, "{No Key Update}");
268  }
269 
270  values[Atnum_pids] = palloc(NCHARS * sizeof(char));
271  snprintf(values[Atnum_pids], NCHARS, "{%d}",
272  BackendXidGetPid(xmax));
273  }
274 
276 
277  /* build a tuple */
278  tuple = BuildTupleFromCStrings(attinmeta, values);
279 
280  /* make the tuple into a datum */
281  result = HeapTupleGetDatum(tuple);
282 
283  /*
284  * no need to pfree what we allocated; it's on a short-lived
285  * memory context anyway
286  */
287 
288  SRF_RETURN_NEXT(funcctx, result);
289  }
290  else
291  {
293  }
294  }
295 
296  heap_endscan(scan);
297  heap_close(mydata->rel, AccessShareLock);
298 
299  SRF_RETURN_DONE(funcctx);
300 }
#define NCHARS
Definition: pgrowlocks.c:53
#define BUFFER_LOCK_UNLOCK
Definition: bufmgr.h:87
PG_FUNCTION_INFO_V1(pgrowlocks)
TypeFuncClass get_call_result_type(FunctionCallInfo fcinfo, Oid *resultTypeId, TupleDesc *resultTupleDesc)
Definition: funcapi.c:211
#define HEAP_XMAX_LOCK_ONLY
Definition: htup_details.h:182
void heap_endscan(HeapScanDesc scan)
Definition: heapam.c:1578
uint32 TransactionId
Definition: c.h:397
HTSU_Result HeapTupleSatisfiesUpdate(HeapTuple htup, CommandId curcid, Buffer buffer)
Definition: tqual.c:460
Oid GetUserId(void)
Definition: miscinit.c:283
#define SRF_IS_FIRSTCALL()
Definition: funcapi.h:285
#define PointerGetDatum(X)
Definition: postgres.h:562
char * pstrdup(const char *in)
Definition: mcxt.c:1077
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:109
Snapshot GetActiveSnapshot(void)
Definition: snapmgr.c:834
#define HEAP_LOCKED_UPGRADED(infomask)
Definition: htup_details.h:238
#define AccessShareLock
Definition: lockdefs.h:36
Datum pgrowlocks(PG_FUNCTION_ARGS)
Definition: pgrowlocks.c:70
return result
Definition: formatting.c:1632
int snprintf(char *str, size_t count, const char *fmt,...) pg_attribute_printf(3
RangeVar * makeRangeVarFromNameList(List *names)
Definition: namespace.c:2980
#define heap_close(r, l)
Definition: heapam.h:97
#define DirectFunctionCall1(func, arg1)
Definition: fmgr.h:584
#define SRF_PERCALL_SETUP()
Definition: funcapi.h:289
int natts
Definition: tupdesc.h:73
HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values)
Definition: execTuples.c:1115
#define PG_GETARG_TEXT_PP(n)
Definition: fmgr.h:273
#define HEAP_XMAX_IS_SHR_LOCKED(infomask)
Definition: htup_details.h:248
HeapTupleHeader t_data
Definition: htup.h:67
#define Atnum_tid
Definition: pgrowlocks.c:62
#define SRF_RETURN_NEXT(_funcctx, _result)
Definition: funcapi.h:291
Relation rel
Definition: pgrowlocks.c:57
PG_MODULE_MAGIC
Definition: pgrowlocks.c:43
#define HeapTupleHeaderGetRawXmax(tup)
Definition: htup_details.h:369
unsigned short uint16
Definition: c.h:267
#define ERROR
Definition: elog.h:43
ItemPointerData t_self
Definition: htup.h:65
static char * buf
Definition: pg_test_fsync.c:66
void aclcheck_error(AclResult aclerr, AclObjectKind objectkind, const char *objectname)
Definition: aclchk.c:3399
AttInMetadata * attinmeta
Definition: funcapi.h:99
HTSU_Result
Definition: snapshot.h:119
#define RelationGetRelationName(relation)
Definition: rel.h:437
List * textToQualifiedNameList(text *textval)
Definition: varlena.c:3189
int BackendXidGetPid(TransactionId xid)
Definition: procarray.c:2402
#define Atnum_modes
Definition: pgrowlocks.c:66
AclResult
Definition: acl.h:170
uintptr_t Datum
Definition: postgres.h:372
#define ACL_SELECT
Definition: parsenodes.h:73
AttInMetadata * TupleDescGetAttInMetadata(TupleDesc tupdesc)
Definition: execTuples.c:1068
void LockBuffer(Buffer buffer, int mode)
Definition: bufmgr.c:3546
#define HEAP_KEYS_UPDATED
Definition: htup_details.h:264
HeapTuple heap_getnext(HeapScanDesc scan, ScanDirection direction)
Definition: heapam.c:1794
#define HEAP_XMAX_IS_MULTI
Definition: htup_details.h:194
Relation heap_openrv(const RangeVar *relation, LOCKMODE lockmode)
Definition: heapam.c:1312
bool is_member_of_role(Oid member, Oid role)
Definition: acl.c:4837
Buffer rs_cbuf
Definition: relscan.h:70
#define NULL
Definition: c.h:229
MemoryContext multi_call_memory_ctx
Definition: funcapi.h:109
#define HeapTupleGetDatum(tuple)
Definition: funcapi.h:222
HeapScanDesc scan
Definition: pgrowlocks.c:58
AclResult pg_class_aclcheck(Oid table_oid, Oid roleid, AclMode mode)
Definition: aclchk.c:4422
static Datum values[MAXATTR]
Definition: bootstrap.c:163
#define Atnum_xids
Definition: pgrowlocks.c:65
void * user_fctx
Definition: funcapi.h:90
void * palloc(Size size)
Definition: mcxt.c:849
#define BUFFER_LOCK_SHARE
Definition: bufmgr.h:88
Definition: c.h:439
#define PG_FUNCTION_ARGS
Definition: fmgr.h:158
#define Atnum_pids
Definition: pgrowlocks.c:67
int ncolumns
Definition: pgrowlocks.c:59
#define HEAP_XMAX_IS_EXCL_LOCKED(infomask)
Definition: htup_details.h:250
CommandId GetCurrentCommandId(bool used)
Definition: xact.c:687
int GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **members, bool from_pgupgrade, bool onlyLock)
Definition: multixact.c:1202
#define elog
Definition: elog.h:219
#define DEFAULT_ROLE_STAT_SCAN_TABLES
Definition: pg_authid.h:110
#define HEAP_XMAX_IS_KEYSHR_LOCKED(infomask)
Definition: htup_details.h:252
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:224
HeapScanDesc heap_beginscan(Relation relation, Snapshot snapshot, int nkeys, ScanKey key)
Definition: heapam.c:1391
Datum tidout(PG_FUNCTION_ARGS)
Definition: tid.c:105
#define RelationGetRelid(relation)
Definition: rel.h:417
#define Atnum_xmax
Definition: pgrowlocks.c:63
#define SRF_RETURN_DONE(_funcctx)
Definition: funcapi.h:309
#define Atnum_ismulti
Definition: pgrowlocks.c:64
#define SRF_FIRSTCALL_INIT()
Definition: funcapi.h:287