Use a lexer and grammar for parsing walsender commands

Makes it easier to parse mainly the BASE_BACKUP command with it's options, and avoids having to manually deal with quoted identifiers in the label (previously broken), and makes it easier to add new commands and options in the future. In passing, refactor the case statement in the walsender to put each command in it's own function.
2025-09-02 04:21:28 +03:00 · 2011-01-14 16:30:33 +01:00
parent 688423d004
commit fcd810c69a
12 changed files with 603 additions and 128 deletions
--- a/src/backend/replication/repl_gram.y
+++ b/src/backend/replication/repl_gram.y
@@ -0,0 +1,143 @@
+%{
+/*-------------------------------------------------------------------------
+ *
+ * repl_gram.y				- Parser for the replication commands
+ *
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/replication/repl_gram.y
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "replication/replnodes.h"
+#include "replication/walsender.h"
+
+/* Result of the parsing is returned here */
+Node *replication_parse_result;
+
+/* Location tracking support --- simpler than bison's default */
+#define YYLLOC_DEFAULT(Current, Rhs, N) \
+	do { \
+		if (N) \
+			(Current) = (Rhs)[1]; \
+		else \
+			(Current) = (Rhs)[0]; \
+	} while (0)
+
+/*
+ * Bison doesn't allocate anything that needs to live across parser calls,
+ * so we can easily have it use palloc instead of malloc.  This prevents
+ * memory leaks if we error out during parsing.  Note this only works with
+ * bison >= 2.0.  However, in bison 1.875 the default is to use alloca()
+ * if possible, so there's not really much problem anyhow, at least if
+ * you're building with gcc.
+ */
+#define YYMALLOC palloc
+#define YYFREE   pfree
+
+#define parser_yyerror(msg)  replication_yyerror(msg, yyscanner)
+#define parser_errposition(pos)  replication_scanner_errposition(pos)
+
+%}
+
+%expect 0
+%name-prefix="replication_yy"
+
+%union {
+		char					*str;
+		bool					boolval;
+
+		XLogRecPtr				recptr;
+		Node					*node;
+}
+
+/* Non-keyword tokens */
+%token <str> SCONST
+%token <recptr> RECPTR
+
+/* Keyword tokens. */
+%token K_BASE_BACKUP
+%token K_IDENTIFY_SYSTEM
+%token K_LABEL
+%token K_PROGRESS
+%token K_START_REPLICATION
+
+%type <node>	command
+%type <node>	base_backup start_replication identify_system
+%type <boolval>	opt_progress
+%type <str>     opt_label
+
+%%
+
+firstcmd: command opt_semicolon
+				{
+					replication_parse_result = $1;
+				}
+			;
+
+opt_semicolon:	';'
+				| /* EMPTY */
+				;
+
+command:
+			identify_system
+			| base_backup
+			| start_replication
+			;
+
+/*
+ * IDENTIFY_SYSTEM
+ */
+identify_system:
+			K_IDENTIFY_SYSTEM
+				{
+					$$ = (Node *) makeNode(IdentifySystemCmd);
+				}
+			;
+
+/*
+ * BASE_BACKUP [LABEL <label>] [PROGRESS]
+ */
+base_backup:
+			K_BASE_BACKUP opt_label opt_progress
+				{
+					BaseBackupCmd *cmd = (BaseBackupCmd *) makeNode(BaseBackupCmd);
+
+					cmd->label = $2;
+					cmd->progress = $3;
+
+					$$ = (Node *) cmd;
+				}
+			;
+
+opt_label: K_LABEL SCONST { $$ = $2; }
+			| /* EMPTY */		{ $$ = NULL; }
+			;
+
+opt_progress: K_PROGRESS		{ $$ = true; }
+			| /* EMPTY */		{ $$ = false; }
+			;
+
+/*
+ * START_REPLICATION %X/%X
+ */
+start_replication:
+			K_START_REPLICATION RECPTR
+				{
+					StartReplicationCmd *cmd;
+
+					cmd = makeNode(StartReplicationCmd);
+					cmd->startpoint = $2;
+
+					$$ = (Node *) cmd;
+				}
+			;
+%%
+
+#include "repl_scanner.c"