From bcac23de73b89b001fbc628d84471a392e928d1c Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Fri, 12 Feb 2016 09:31:16 -0500 Subject: [PATCH] Introduce extensible node types. An extensible node is always tagged T_Extensible, but the extnodename field identifies it more specifically; it may also include arbitrary private data. Extensible nodes can be copied, tested for equality, serialized, and deserialized, but the core system doesn't know anything about them otherwise. Some extensions may find it useful to include these nodes in fdw_private or custom_private lists in lieu of arm-wrestling their data into a format that the core code can understand. Along the way, so as not to burden the authors of such extensible node types too much, expose the functions for writing serialized tokens, and for serializing and deserializing bitmapsets. KaiGai Kohei, per a design suggested by me. Reviewed by Andres Freund and by me, and further edited by me. --- src/backend/nodes/Makefile | 2 +- src/backend/nodes/copyfuncs.c | 29 +++++++++++ src/backend/nodes/equalfuncs.c | 27 ++++++++++ src/backend/nodes/extensible.c | 92 ++++++++++++++++++++++++++++++++++ src/backend/nodes/outfuncs.c | 40 +++++++++++++++ src/backend/nodes/readfuncs.c | 40 +++++++++++++++ src/include/nodes/extensible.h | 72 ++++++++++++++++++++++++++ src/include/nodes/nodes.h | 12 +++++ 8 files changed, 313 insertions(+), 1 deletion(-) create mode 100644 src/backend/nodes/extensible.c create mode 100644 src/include/nodes/extensible.h diff --git a/src/backend/nodes/Makefile b/src/backend/nodes/Makefile index fe2e46053e6..0b1e98c0190 100644 --- a/src/backend/nodes/Makefile +++ b/src/backend/nodes/Makefile @@ -13,7 +13,7 @@ top_builddir = ../../.. include $(top_builddir)/src/Makefile.global OBJS = nodeFuncs.o nodes.o list.o bitmapset.o tidbitmap.o \ - copyfuncs.o equalfuncs.o makefuncs.o \ + copyfuncs.o equalfuncs.o extensible.o makefuncs.o \ outfuncs.o readfuncs.o print.o read.o params.o value.o include $(top_srcdir)/src/backend/common.mk diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index e54d1744b0a..a9e9cc379b8 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -23,6 +23,7 @@ #include "postgres.h" #include "miscadmin.h" +#include "nodes/extensible.h" #include "nodes/plannodes.h" #include "nodes/relation.h" #include "utils/datum.h" @@ -4165,6 +4166,27 @@ _copyList(const List *from) return new; } +/* **************************************************************** + * extensible.h copy functions + * **************************************************************** + */ +static ExtensibleNode * +_copyExtensibleNode(const ExtensibleNode *from) +{ + ExtensibleNode *newnode; + const ExtensibleNodeMethods *methods; + + methods = GetExtensibleNodeMethods(from->extnodename, false); + newnode = (ExtensibleNode *) newNode(methods->node_size, + T_ExtensibleNode); + COPY_STRING_FIELD(extnodename); + + /* copy the private fields */ + methods->nodeCopy(newnode, from); + + return newnode; +} + /* **************************************************************** * value.h copy functions * **************************************************************** @@ -4544,6 +4566,13 @@ copyObject(const void *from) retval = list_copy(from); break; + /* + * EXTENSIBLE NODES + */ + case T_ExtensibleNode: + retval = _copyExtensibleNode(from); + break; + /* * PARSE NODES */ diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c index 08ccc0de664..b9c39594283 100644 --- a/src/backend/nodes/equalfuncs.c +++ b/src/backend/nodes/equalfuncs.c @@ -29,6 +29,7 @@ #include "postgres.h" +#include "nodes/extensible.h" #include "nodes/relation.h" #include "utils/datum.h" @@ -871,6 +872,25 @@ _equalPlaceHolderInfo(const PlaceHolderInfo *a, const PlaceHolderInfo *b) return true; } +/* + * Stuff from extensible.h + */ +static bool +_equalExtensibleNode(const ExtensibleNode *a, const ExtensibleNode *b) +{ + const ExtensibleNodeMethods *methods; + + COMPARE_STRING_FIELD(extnodename); + + /* At this point, we know extnodename is the same for both nodes. */ + methods = GetExtensibleNodeMethods(a->extnodename, false); + + /* compare the private fields */ + if (!methods->nodeEqual(a, b)) + return false; + + return true; +} /* * Stuff from parsenodes.h @@ -2873,6 +2893,13 @@ equal(const void *a, const void *b) retval = _equalValue(a, b); break; + /* + * EXTENSIBLE NODES + */ + case T_ExtensibleNode: + retval = _equalExtensibleNode(a, b); + break; + /* * PARSE NODES */ diff --git a/src/backend/nodes/extensible.c b/src/backend/nodes/extensible.c new file mode 100644 index 00000000000..8fb4767d4d2 --- /dev/null +++ b/src/backend/nodes/extensible.c @@ -0,0 +1,92 @@ +/*------------------------------------------------------------------------- + * + * extensible.c + * Support for extensible node types + * + * Loadable modules can define what are in effect new types of nodes using + * the routines in this file. All such nodes are flagged T_ExtensibleNode, + * with the extnodename field distinguishing the specific type. Use + * RegisterExtensibleNodeMethods to register a new type of extensible node, + * and GetExtensibleNodeMethods to get information about a previously + * registered type of extensible node. + * + * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/nodes/extensible.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "nodes/extensible.h" +#include "utils/hsearch.h" + +static HTAB *extensible_node_methods = NULL; + +typedef struct +{ + char extnodename[EXTNODENAME_MAX_LEN]; + const ExtensibleNodeMethods *methods; +} ExtensibleNodeEntry; + +/* + * Register a new type of extensible node. + */ +void +RegisterExtensibleNodeMethods(const ExtensibleNodeMethods *methods) +{ + ExtensibleNodeEntry *entry; + bool found; + + if (extensible_node_methods == NULL) + { + HASHCTL ctl; + + memset(&ctl, 0, sizeof(HASHCTL)); + ctl.keysize = NAMEDATALEN; + ctl.entrysize = sizeof(ExtensibleNodeEntry); + extensible_node_methods = hash_create("Extensible Node Methods", + 100, &ctl, HASH_ELEM); + } + + Assert(strlen(methods->extnodename) <= EXTNODENAME_MAX_LEN); + + entry = (ExtensibleNodeEntry *) hash_search(extensible_node_methods, + methods->extnodename, + HASH_ENTER, &found); + if (found) + ereport(ERROR, + (errcode(ERRCODE_DUPLICATE_OBJECT), + errmsg("extensible node type \"%s\" already exists", + methods->extnodename))); + + entry->methods = methods; +} + +/* + * Get the methods for a given type of extensible node. + */ +const ExtensibleNodeMethods * +GetExtensibleNodeMethods(const char *extnodename, bool missing_ok) +{ + ExtensibleNodeEntry *entry = NULL; + + if (extensible_node_methods != NULL) + entry = (ExtensibleNodeEntry *) hash_search(extensible_node_methods, + extnodename, + HASH_FIND, NULL); + + if (!entry) + { + if (missing_ok) + return NULL; + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("ExtensibleNodeMethods \"%s\" was not registered", + extnodename))); + } + + return entry->methods; +} diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c index 3e1c3e6be57..28d983c9a87 100644 --- a/src/backend/nodes/outfuncs.c +++ b/src/backend/nodes/outfuncs.c @@ -26,6 +26,7 @@ #include #include "lib/stringinfo.h" +#include "nodes/extensible.h" #include "nodes/plannodes.h" #include "nodes/relation.h" #include "utils/datum.h" @@ -140,6 +141,13 @@ _outToken(StringInfo str, const char *s) } } +/* for use by extensions which define extensible nodes */ +void +outToken(StringInfo str, const char *s) +{ + _outToken(str, s); +} + static void _outList(StringInfo str, const List *node) { @@ -196,6 +204,13 @@ _outBitmapset(StringInfo str, const Bitmapset *bms) appendStringInfoChar(str, ')'); } +/* for use by extensions which define extensible nodes */ +void +outBitmapset(StringInfo str, const Bitmapset *bms) +{ + _outBitmapset(str, bms); +} + /* * Print the value of a Datum given its type. */ @@ -2112,6 +2127,27 @@ _outPlannerParamItem(StringInfo str, const PlannerParamItem *node) WRITE_INT_FIELD(paramId); } +/***************************************************************************** + * + * Stuff from extensible.h + * + *****************************************************************************/ + +static void +_outExtensibleNode(StringInfo str, const ExtensibleNode *node) +{ + const ExtensibleNodeMethods *methods; + + methods = GetExtensibleNodeMethods(node->extnodename, false); + + WRITE_NODE_TYPE("EXTENSIBLENODE"); + + WRITE_STRING_FIELD(extnodename); + + /* serialize the private fields */ + methods->nodeOut(str, node); +} + /***************************************************************************** * * Stuff from parsenodes.h. @@ -3367,6 +3403,10 @@ _outNode(StringInfo str, const void *obj) _outPlannerParamItem(str, obj); break; + case T_ExtensibleNode: + _outExtensibleNode(str, obj); + break; + case T_CreateStmt: _outCreateStmt(str, obj); break; diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c index e4d41ee95b2..e6e6f2981c2 100644 --- a/src/backend/nodes/readfuncs.c +++ b/src/backend/nodes/readfuncs.c @@ -29,6 +29,7 @@ #include #include "fmgr.h" +#include "nodes/extensible.h" #include "nodes/parsenodes.h" #include "nodes/plannodes.h" #include "nodes/readfuncs.h" @@ -218,6 +219,14 @@ _readBitmapset(void) return result; } +/* + * for use by extensions which define extensible nodes + */ +Bitmapset * +readBitmapset(void) +{ + return _readBitmapset(); +} /* * _readQuery @@ -2219,6 +2228,35 @@ _readAlternativeSubPlan(void) READ_DONE(); } +/* + * _readExtensibleNode + */ +static ExtensibleNode * +_readExtensibleNode(void) +{ + const ExtensibleNodeMethods *methods; + ExtensibleNode *local_node; + const char *extnodename; + READ_TEMP_LOCALS(); + + token = pg_strtok(&length); /* skip: extnodename */ + token = pg_strtok(&length); /* get extnodename */ + + extnodename = nullable_string(token, length); + if (!extnodename) + elog(ERROR, "extnodename has to be supplied"); + methods = GetExtensibleNodeMethods(extnodename, false); + + local_node = (ExtensibleNode *) newNode(methods->node_size, + T_ExtensibleNode); + local_node->extnodename = extnodename; + + /* deserialize the private fields */ + methods->nodeRead(local_node); + + READ_DONE(); +} + /* * parseNodeString * @@ -2447,6 +2485,8 @@ parseNodeString(void) return_value = _readSubPlan(); else if (MATCH("ALTERNATIVESUBPLAN", 18)) return_value = _readAlternativeSubPlan(); + else if (MATCH("EXTENSIBLENODE", 14)) + return_value = _readExtensibleNode(); else { elog(ERROR, "badly formatted node string \"%.32s\"...", token); diff --git a/src/include/nodes/extensible.h b/src/include/nodes/extensible.h new file mode 100644 index 00000000000..96ae7bc9291 --- /dev/null +++ b/src/include/nodes/extensible.h @@ -0,0 +1,72 @@ +/*------------------------------------------------------------------------- + * + * extensible.h + * Definitions for extensible node type + * + * + * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/nodes/extensible.h + * + *------------------------------------------------------------------------- + */ +#ifndef EXTENSIBLE_H +#define EXTENSIBLE_H + +#include "nodes/nodes.h" + +#define EXTNODENAME_MAX_LEN 64 + +/* + * An extensible node is a new type of node defined by an extension. The + * type is always T_ExtensibleNode, while the extnodename identifies the + * specific type of node. extnodename can be looked up to find the + * ExtensibleNodeMethods for this node type. + */ +typedef struct ExtensibleNode +{ + NodeTag type; + const char *extnodename; /* identifier of ExtensibleNodeMethods */ +} ExtensibleNode; + +/* + * node_size is the size of an extensible node of this type in bytes. + * + * nodeCopy is a function which performs a deep copy from oldnode to newnode. + * It does not need to copy type or extnodename, which are copied by the + * core system. + * + * nodeEqual is a function which performs a deep equality comparison between + * a and b and returns true or false accordingly. It does not need to compare + * type or extnodename, which are compared by the core system. + * + * nodeOut is a serialization function for the node type. It should use the + * output conventions typical for outfuncs.c. It does not need to output + * type or extnodename; the core system handles those. + * + * nodeRead is a deserialization function for the node type. It does not need + * to read type or extnodename; the core system handles those. It should fetch + * the next token using pg_strtok() from the current input stream, and then + * reconstruct the private fields according to the manner in readfuncs.c. + * + * All callbacks are mandatory. + */ +typedef struct ExtensibleNodeMethods +{ + const char *extnodename; + Size node_size; + void (*nodeCopy)(struct ExtensibleNode *newnode, + const struct ExtensibleNode *oldnode); + bool (*nodeEqual)(const struct ExtensibleNode *a, + const struct ExtensibleNode *b); + void (*nodeOut)(struct StringInfoData *str, + const struct ExtensibleNode *node); + void (*nodeRead)(struct ExtensibleNode *node); +} ExtensibleNodeMethods; + +extern void RegisterExtensibleNodeMethods(const ExtensibleNodeMethods *method); +extern const ExtensibleNodeMethods *GetExtensibleNodeMethods(const char *name, + bool missing_ok); + +#endif /* EXTENSIBLE_H */ diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h index cf09db4e5fe..c407fa2cd49 100644 --- a/src/include/nodes/nodes.h +++ b/src/include/nodes/nodes.h @@ -275,6 +275,11 @@ typedef enum NodeTag T_IntList, T_OidList, + /* + * TAGS FOR EXTENSIBLE NODES (extensible.h) + */ + T_ExtensibleNode, + /* * TAGS FOR STATEMENT NODES (mostly in parsenodes.h) */ @@ -527,10 +532,17 @@ extern PGDLLIMPORT Node *newNodeMacroHolder; */ extern char *nodeToString(const void *obj); +struct Bitmapset; /* not to include bitmapset.h here */ +struct StringInfoData; /* not to include stringinfo.h here */ +extern void outToken(struct StringInfoData *str, const char *s); +extern void outBitmapset(struct StringInfoData *str, + const struct Bitmapset *bms); + /* * nodes/{readfuncs.c,read.c} */ extern void *stringToNode(char *str); +extern struct Bitmapset *readBitmapset(void); /* * nodes/copyfuncs.c -- 2.30.2