Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * tcn.c
4 : : * triggered change notification support for PostgreSQL
5 : : *
6 : : * Portions Copyright (c) 2011-2024, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * contrib/tcn/tcn.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : :
16 : : #include "postgres.h"
17 : :
18 : : #include "access/htup_details.h"
19 : : #include "commands/async.h"
20 : : #include "commands/trigger.h"
21 : : #include "executor/spi.h"
22 : : #include "lib/stringinfo.h"
23 : : #include "utils/rel.h"
24 : : #include "utils/syscache.h"
25 : :
4469 rhaas@postgresql.org 26 :CBC 2 : PG_MODULE_MAGIC;
27 : :
28 : : /*
29 : : * Copy from s (for source) to r (for result), wrapping with q (quote)
30 : : * characters and doubling any quote characters found.
31 : : */
32 : : static void
33 : 15 : strcpy_quoted(StringInfo r, const char *s, const char q)
34 : : {
35 [ - + ]: 15 : appendStringInfoCharMacro(r, q);
36 [ + + ]: 70 : while (*s)
37 : : {
38 [ - + ]: 55 : if (*s == q)
4469 rhaas@postgresql.org 39 [ # # ]:UBC 0 : appendStringInfoCharMacro(r, q);
4469 rhaas@postgresql.org 40 [ - + ]:CBC 55 : appendStringInfoCharMacro(r, *s);
41 : 55 : s++;
42 : : }
43 [ - + ]: 15 : appendStringInfoCharMacro(r, q);
44 : 15 : }
45 : :
46 : : /*
47 : : * triggered_change_notification
48 : : *
49 : : * This trigger function will send a notification of data modification with
50 : : * primary key values. The channel will be "tcn" unless the trigger is
51 : : * created with a parameter, in which case that parameter will be used.
52 : : */
53 : 2 : PG_FUNCTION_INFO_V1(triggered_change_notification);
54 : :
55 : : Datum
56 : 5 : triggered_change_notification(PG_FUNCTION_ARGS)
57 : : {
58 : 5 : TriggerData *trigdata = (TriggerData *) fcinfo->context;
59 : : Trigger *trigger;
60 : : int nargs;
61 : : HeapTuple trigtuple;
62 : : Relation rel;
63 : : TupleDesc tupdesc;
64 : : char *channel;
65 : : char operation;
66 : 5 : StringInfo payload = makeStringInfo();
67 : : bool foundPK;
68 : :
69 : : List *indexoidlist;
70 : : ListCell *indexoidscan;
71 : :
72 : : /* make sure it's called as a trigger */
73 [ + - - + ]: 5 : if (!CALLED_AS_TRIGGER(fcinfo))
4469 rhaas@postgresql.org 74 [ # # ]:UBC 0 : ereport(ERROR,
75 : : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
76 : : errmsg("triggered_change_notification: must be called as trigger")));
77 : :
78 : : /* and that it's called after the change */
4469 rhaas@postgresql.org 79 [ - + ]:CBC 5 : if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
4469 rhaas@postgresql.org 80 [ # # ]:UBC 0 : ereport(ERROR,
81 : : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
82 : : errmsg("triggered_change_notification: must be called after the change")));
83 : :
84 : : /* and that it's called for each row */
4469 rhaas@postgresql.org 85 [ - + ]:CBC 5 : if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
4469 rhaas@postgresql.org 86 [ # # ]:UBC 0 : ereport(ERROR,
87 : : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
88 : : errmsg("triggered_change_notification: must be called for each row")));
89 : :
4469 rhaas@postgresql.org 90 [ + + ]:CBC 5 : if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
91 : 2 : operation = 'I';
92 [ + + ]: 3 : else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
93 : 1 : operation = 'U';
94 [ + - ]: 2 : else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
95 : 2 : operation = 'D';
96 : : else
97 : : {
4469 rhaas@postgresql.org 98 [ # # ]:UBC 0 : elog(ERROR, "triggered_change_notification: trigger fired by unrecognized operation");
99 : : operation = 'X'; /* silence compiler warning */
100 : : }
101 : :
4469 rhaas@postgresql.org 102 :CBC 5 : trigger = trigdata->tg_trigger;
103 : 5 : nargs = trigger->tgnargs;
104 [ - + ]: 5 : if (nargs > 1)
4469 rhaas@postgresql.org 105 [ # # ]:UBC 0 : ereport(ERROR,
106 : : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
107 : : errmsg("triggered_change_notification: must not be called with more than one parameter")));
108 : :
4469 rhaas@postgresql.org 109 [ - + ]:CBC 5 : if (nargs == 0)
4469 rhaas@postgresql.org 110 :UBC 0 : channel = "tcn";
111 : : else
4469 rhaas@postgresql.org 112 :CBC 5 : channel = trigger->tgargs[0];
113 : :
114 : : /* get tuple data */
115 : 5 : trigtuple = trigdata->tg_trigtuple;
116 : 5 : rel = trigdata->tg_relation;
117 : 5 : tupdesc = rel->rd_att;
118 : :
119 : 5 : foundPK = false;
120 : :
121 : : /*
122 : : * Get the list of index OIDs for the table from the relcache, and look up
123 : : * each one in the pg_index syscache until we find one marked primary key
124 : : * (hopefully there isn't more than one such).
125 : : */
126 : 5 : indexoidlist = RelationGetIndexList(rel);
127 : :
128 [ + - + - : 5 : foreach(indexoidscan, indexoidlist)
+ - ]
129 : : {
130 : 5 : Oid indexoid = lfirst_oid(indexoidscan);
131 : : HeapTuple indexTuple;
132 : : Form_pg_index index;
133 : :
134 : 5 : indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
2489 tgl@sss.pgh.pa.us 135 [ - + ]: 5 : if (!HeapTupleIsValid(indexTuple)) /* should not happen */
4469 rhaas@postgresql.org 136 [ # # ]:UBC 0 : elog(ERROR, "cache lookup failed for index %u", indexoid);
4469 rhaas@postgresql.org 137 :CBC 5 : index = (Form_pg_index) GETSTRUCT(indexTuple);
138 : : /* we're only interested if it is the primary key and valid */
1935 peter_e@gmx.net 139 [ + - + - ]: 5 : if (index->indisprimary && index->indisvalid)
140 : : {
2180 tgl@sss.pgh.pa.us 141 : 5 : int indnkeyatts = index->indnkeyatts;
142 : :
2199 teodor@sigaev.ru 143 [ + - ]: 5 : if (indnkeyatts > 0)
144 : : {
145 : : int i;
146 : :
4469 rhaas@postgresql.org 147 : 5 : foundPK = true;
148 : :
149 : 5 : strcpy_quoted(payload, RelationGetRelationName(rel), '"');
150 [ - + ]: 5 : appendStringInfoCharMacro(payload, ',');
151 [ - + ]: 5 : appendStringInfoCharMacro(payload, operation);
152 : :
2199 teodor@sigaev.ru 153 [ + + ]: 10 : for (i = 0; i < indnkeyatts; i++)
154 : : {
4469 rhaas@postgresql.org 155 : 5 : int colno = index->indkey.values[i];
2429 andres@anarazel.de 156 : 5 : Form_pg_attribute attr = TupleDescAttr(tupdesc, colno - 1);
157 : :
4469 rhaas@postgresql.org 158 [ - + ]: 5 : appendStringInfoCharMacro(payload, ',');
2429 andres@anarazel.de 159 : 5 : strcpy_quoted(payload, NameStr(attr->attname), '"');
4469 rhaas@postgresql.org 160 [ - + ]: 5 : appendStringInfoCharMacro(payload, '=');
161 : 5 : strcpy_quoted(payload, SPI_getvalue(trigtuple, tupdesc, colno), '\'');
162 : : }
163 : :
164 : 5 : Async_Notify(channel, payload->data);
165 : : }
166 : 5 : ReleaseSysCache(indexTuple);
167 : 5 : break;
168 : : }
4469 rhaas@postgresql.org 169 :UBC 0 : ReleaseSysCache(indexTuple);
170 : : }
171 : :
4469 rhaas@postgresql.org 172 :CBC 5 : list_free(indexoidlist);
173 : :
174 [ - + ]: 5 : if (!foundPK)
4469 rhaas@postgresql.org 175 [ # # ]:UBC 0 : ereport(ERROR,
176 : : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
177 : : errmsg("triggered_change_notification: must be called on a table with a primary key")));
178 : :
2489 tgl@sss.pgh.pa.us 179 :CBC 5 : return PointerGetDatum(NULL); /* after trigger; value doesn't matter */
180 : : }
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