mirror of
https://github.com/postgres/postgres.git
synced 2025-10-22 14:32:25 +03:00
- Finished major rewrite to use new protocol version
- Really prepare statements - Added more regression tests - Added auto-prepare mode - Use '$n' for positional variables, '?' is still possible via ecpg option - Cleaned up the sources a little bit
This commit is contained in:
Michael Meskes
@@ -1,4 +1,4 @@
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/* $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/prepare.c,v 1.18 2006/10/04 00:30:11 momjian Exp $ */
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/* $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/prepare.c,v 1.19 2007/08/14 10:01:52 meskes Exp $ */
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#define POSTGRES_ECPG_INTERNAL
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#include "postgres_fe.h"
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@@ -13,11 +13,28 @@
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static struct prepared_statement
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{
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char *name;
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char *name;
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bool prepared;
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struct statement *stmt;
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struct prepared_statement *next;
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} *prep_stmts = NULL;
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#define STMTID_SIZE 32
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typedef struct
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{
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int lineno;
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char stmtID[STMTID_SIZE];
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char *ecpgQuery;
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long execs; /* # of executions */
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char *connection; /* connection for the statement */
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} stmtCacheEntry;
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static int nextStmtID = 1;
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static int stmtCacheNBuckets = 2039; /* # buckets - a prime # */
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static int stmtCacheEntPerBucket = 8; /* # entries/bucket */
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static stmtCacheEntry stmtCacheEntries[16384] = {{0,{0},0,0,0}};
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static bool
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isvarchar(unsigned char c)
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{
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@@ -33,43 +50,68 @@ isvarchar(unsigned char c)
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return (false);
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}
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static void
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replace_variables(char *text)
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static bool
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replace_variables(char **text, int lineno, bool questionmarks)
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{
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char *ptr = text;
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bool string = false;
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bool string = false;
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int counter = 1, ptr = 0;
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for (; *ptr != '\0'; ptr++)
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for (; (*text)[ptr] != '\0'; ptr++)
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{
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if (*ptr == '\'')
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if ((*text)[ptr] == '\'')
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string = string ? false : true;
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if (!string && *ptr == ':')
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if (string || (((*text)[ptr] != ':') && ((*text)[ptr] != '?')))
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continue;
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if (((*text)[ptr] == ':') && ((*text)[ptr+1] == ':'))
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ptr += 2; /* skip '::' */
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else
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{
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if (ptr[1] == ':')
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ptr += 2; /* skip '::' */
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else
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int len;
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int buffersize = sizeof(int) * CHAR_BIT * 10 / 3; /* a rough guess of the size we need */
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char *buffer, *newcopy;
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if (!(buffer = (char *) ECPGalloc(buffersize, lineno)))
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return false;
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snprintf(buffer, buffersize, "$%d", counter++);
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for (len=1; (*text)[ptr+len] && isvarchar((*text)[ptr+len]); len++);
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if (!(newcopy = (char *) ECPGalloc(strlen(*text) - len + strlen(buffer) + 1, lineno)))
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{
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*ptr = '?';
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for (++ptr; *ptr && isvarchar(*ptr); ptr++)
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*ptr = ' ';
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if (*ptr == '\0') /* we reached the end */
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ptr--; /* since we will ptr++ in the top level for
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* loop */
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ECPGfree(buffer);
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return false;
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}
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strncpy(newcopy, *text, ptr);
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strcpy(newcopy + ptr, buffer);
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strcat(newcopy, (*text) + ptr + len);
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ECPGfree(*text);
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ECPGfree(buffer);
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*text = newcopy;
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if ((*text)[ptr] == '\0') /* we reached the end */
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ptr--; /* since we will (*text)[ptr]++ in the top level for
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* loop */
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}
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}
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return true;
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}
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/* handle the EXEC SQL PREPARE statement */
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bool
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ECPGprepare(int lineno, const char *name, const char *variable)
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ECPGprepare(int lineno, const char *connection_name, const int questionmarks, const char *name, const char *variable)
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{
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struct statement *stmt;
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struct prepared_statement *this;
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struct sqlca_t *sqlca = ECPGget_sqlca();
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PGresult *query;
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ECPGinit_sqlca(sqlca);
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/* check if we already have prepared this statement */
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for (this = prep_stmts; this != NULL && strcmp(this->name, name) != 0; this = this->next);
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if (this)
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@@ -93,18 +135,30 @@ ECPGprepare(int lineno, const char *name, const char *variable)
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/* create statement */
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stmt->lineno = lineno;
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stmt->connection = NULL;
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stmt->connection = ECPGget_connection(connection_name);
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stmt->command = ECPGstrdup(variable, lineno);
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stmt->inlist = stmt->outlist = NULL;
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/* if we have C variables in our statment replace them with '?' */
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replace_variables(stmt->command);
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replace_variables(&(stmt->command), lineno, questionmarks);
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/* add prepared statement to our list */
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this->name = ECPGstrdup(name, lineno);
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this->name = (char *) name;
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this->stmt = stmt;
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ECPGlog("ECPGprepare line %d: QUERY: %s\n", stmt->lineno, stmt->command);
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/* and finally really prepare the statement */
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query = PQprepare(stmt->connection->connection, name, stmt->command, 0, NULL);
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if (!ECPGcheck_PQresult(query, stmt->lineno, stmt->connection->connection, stmt->compat))
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{
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ECPGfree(stmt->command);
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ECPGfree(this);
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ECPGfree(stmt);
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return false;
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}
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ECPGlog("ECPGprepare line %d: NAME: %s QUERY: %s\n", stmt->lineno, name, stmt->command);
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PQclear(query);
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this->prepared = true;
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if (prep_stmts == NULL)
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this->next = NULL;
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@@ -115,13 +169,57 @@ ECPGprepare(int lineno, const char *name, const char *variable)
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return true;
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}
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static bool
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deallocate_one(int lineno, const char *name)
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{
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struct prepared_statement *this,
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*prev;
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/* check if we really have prepared this statement */
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for (this = prep_stmts, prev = NULL; this != NULL && strcmp(this->name, name) != 0; prev = this, this = this->next);
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if (this)
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{
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/* first deallocate the statement in the backend */
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if (this->prepared)
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{
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char *text;
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PGresult *query;
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if (!(text = (char *) ECPGalloc(strlen("deallocate \"\" ") + strlen(this->name), this->stmt->lineno)))
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return false;
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else
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{
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sprintf(text, "deallocate \"%s\"", this->name);
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query = PQexec(this->stmt->connection->connection, text);
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ECPGfree(text);
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if (!ECPGcheck_PQresult(query, lineno, this->stmt->connection->connection, this->stmt->compat))
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return false;
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PQclear(query);
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}
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}
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/* okay, free all the resources */
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ECPGfree(this->stmt->command);
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ECPGfree(this->stmt);
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if (prev != NULL)
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prev->next = this->next;
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else
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prep_stmts = this->next;
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ECPGfree(this);
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return true;
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}
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return false;
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}
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/* handle the EXEC SQL DEALLOCATE PREPARE statement */
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bool
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ECPGdeallocate(int lineno, int c, const char *name)
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{
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bool ret = ECPGdeallocate_one(lineno, name);
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bool ret = deallocate_one(lineno, name);
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enum COMPAT_MODE compat = c;
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ECPGlog("ECPGdeallocate line %d: NAME: %s\n", lineno, name);
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if (INFORMIX_MODE(compat))
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{
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/*
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@@ -138,37 +236,12 @@ ECPGdeallocate(int lineno, int c, const char *name)
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}
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bool
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ECPGdeallocate_one(int lineno, const char *name)
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{
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struct prepared_statement *this,
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*prev;
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/* check if we really have prepared this statement */
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for (this = prep_stmts, prev = NULL; this != NULL && strcmp(this->name, name) != 0; prev = this, this = this->next);
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if (this)
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{
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/* okay, free all the resources */
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ECPGfree(this->name);
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ECPGfree(this->stmt->command);
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ECPGfree(this->stmt);
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if (prev != NULL)
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prev->next = this->next;
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else
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prep_stmts = this->next;
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ECPGfree(this);
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return true;
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}
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return false;
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}
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bool
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ECPGdeallocate_all(int lineno)
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ECPGdeallocate_all(int lineno, int compat)
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{
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/* deallocate all prepared statements */
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while (prep_stmts != NULL)
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{
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bool b = ECPGdeallocate(lineno, ECPG_COMPAT_PGSQL, prep_stmts->name);
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bool b = ECPGdeallocate(lineno, compat, prep_stmts->name);
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if (!b)
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return false;
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@@ -177,12 +250,204 @@ ECPGdeallocate_all(int lineno)
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return true;
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}
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char *
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ECPGprepared(const char *name, int lineno)
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{
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struct prepared_statement *this;
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for (this = prep_stmts; this != NULL && ((strcmp(this->name, name) != 0) || this->prepared == false); this = this->next);
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return (this) ? this->stmt->command : NULL;
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}
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/* return the prepared statement */
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char *
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ECPGprepared_statement(const char *name)
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ECPGprepared_statement(const char *name, int lineno)
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{
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struct prepared_statement *this;
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for (this = prep_stmts; this != NULL && strcmp(this->name, name) != 0; this = this->next);
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return (this) ? this->stmt->command : NULL;
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}
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/*
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* hash a SQL statement - returns entry # of first entry in the bucket
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*/
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static int
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HashStmt(const char *ecpgQuery)
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{
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int stmtIx, bucketNo, hashLeng, stmtLeng;
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long long hashVal, rotVal;
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stmtLeng = strlen(ecpgQuery);
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hashLeng = 50; /* use 1st 50 characters of statement */
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if(hashLeng > stmtLeng) /* if the statement isn't that long */
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hashLeng = stmtLeng; /* use its actual length */
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hashVal = 0;
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for(stmtIx = 0; stmtIx < hashLeng; ++stmtIx)
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{
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hashVal = hashVal + (int) ecpgQuery[stmtIx];
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hashVal = hashVal << 13;
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rotVal = (hashVal & 0x1fff00000000LL) >> 32;
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hashVal = (hashVal & 0xffffffffLL) | rotVal;
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}
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bucketNo = hashVal % stmtCacheNBuckets;
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bucketNo += 1; /* don't use bucket # 0 */
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return (bucketNo * stmtCacheEntPerBucket);
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}
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/*
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* search the statement cache - search for entry with matching ECPG-format query
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* Returns entry # in cache if found
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* OR zero if not present (zero'th entry isn't used)
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*/
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static int
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SearchStmtCache(const char *ecpgQuery)
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{
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int entNo, entIx;
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/* hash the statement */
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entNo = HashStmt(ecpgQuery);
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/* search the cache */
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for(entIx = 0; entIx < stmtCacheEntPerBucket; ++entIx)
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{
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if(stmtCacheEntries[entNo].stmtID[0]) /* check if entry is in use */
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{
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if(!strcmp(ecpgQuery, stmtCacheEntries[entNo].ecpgQuery))
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break; /* found it */
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}
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++entNo; /* incr entry # */
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}
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/* if entry wasn't found - set entry # to zero */
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if(entIx >= stmtCacheEntPerBucket)
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entNo = 0;
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return(entNo);
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}
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/*
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* free an entry in the statement cache
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* Returns entry # in cache used
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* OR negative error code
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*/
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static int
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ECPGfreeStmtCacheEntry(int entNo) /* entry # to free */
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{
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stmtCacheEntry *entry;
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PGresult *results;
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char deallocText[100];
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struct connection *con;
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entry = &stmtCacheEntries[entNo];
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if(!entry->stmtID[0]) /* return if the entry isn't in use */
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return(0);
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con = ECPGget_connection(entry->connection);
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/* free the server resources for the statement */
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ECPGlog("ECPGfreeStmtCacheEntry line %d: deallocate %s, cache entry #%d\n", entry->lineno, entry->stmtID, entNo);
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sprintf(deallocText, "DEALLOCATE PREPARE %s", entry->stmtID);
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results = PQexec(con->connection, deallocText);
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if (!ECPGcheck_PQresult(results, entry->lineno, con->connection, ECPG_COMPAT_PGSQL))
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return(-1);
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PQclear(results);
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entry->stmtID[0] = '\0';
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/* free the memory used by the cache entry */
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if(entry->ecpgQuery)
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{
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ECPGfree(entry->ecpgQuery);
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entry->ecpgQuery = 0;
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}
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return(entNo);
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}
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/*
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* add an entry to the statement cache
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* returns entry # in cache used OR negative error code
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*/
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static int
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AddStmtToCache(int lineno, /* line # of statement */
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char *stmtID, /* statement ID */
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const char *connection, /* connection */
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const char *ecpgQuery) /* query */
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{
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int ix, initEntNo, luEntNo, entNo;
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stmtCacheEntry *entry;
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/* hash the statement */
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initEntNo = HashStmt(ecpgQuery);
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/* search for an unused entry */
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entNo = initEntNo; /* start with the initial entry # for the bucket */
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luEntNo = initEntNo; /* use it as the initial 'least used' entry */
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for(ix = 0; ix < stmtCacheEntPerBucket; ++ix)
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{
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entry = &stmtCacheEntries[entNo];
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if(!entry->stmtID[0]) /* unused entry - use it */
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break;
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if(entry->execs < stmtCacheEntries[luEntNo].execs)
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luEntNo = entNo; /* save new 'least used' entry */
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++entNo; /* increment entry # */
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}
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/* if no unused entries were found - use the 'least used' entry found in the bucket */
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if(ix >= stmtCacheEntPerBucket) /* if no unused entries were found */
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entNo = luEntNo; /* re-use the 'least used' entry */
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/* 'entNo' is the entry to use - make sure its free */
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if (ECPGfreeStmtCacheEntry(entNo) < 0)
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return (-1);
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/* add the query to the entry */
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entry = &stmtCacheEntries[entNo];
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entry->lineno = lineno;
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entry->ecpgQuery = ECPGstrdup(ecpgQuery, lineno);
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entry->connection = (char *)connection;
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entry->execs = 0;
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memcpy(entry->stmtID, stmtID, sizeof(entry->stmtID));
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return(entNo);
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}
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/* handle cache and preparation of statments in auto-prepare mode */
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bool
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ECPGauto_prepare(int lineno, const char *connection_name, const int questionmarks, char **name, const char *query)
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{
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int entNo;
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/* search the statement cache for this statement */
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entNo = SearchStmtCache(query);
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/* if not found - add the statement to the cache */
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if(entNo)
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{
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ECPGlog("ECPGauto_prepare line %d: stmt found in cache, entry %d\n", lineno, entNo);
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*name = ECPGstrdup(stmtCacheEntries[entNo].stmtID, lineno);
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}
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else
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{
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ECPGlog("ECPGauto_prepare line %d: stmt not in cache; inserting\n", lineno);
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/* generate a statement ID */
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*name = (char *) ECPGalloc(STMTID_SIZE, lineno);
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sprintf(*name, "ecpg%d", nextStmtID++);
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if (!ECPGprepare(lineno, connection_name, questionmarks, ECPGstrdup(*name, lineno), query))
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return(false);
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if (AddStmtToCache(lineno, *name, connection_name, query) < 0)
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return(false);
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}
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/* increase usage counter */
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stmtCacheEntries[entNo].execs++;
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return(true);
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}
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