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Better table existence test.

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Copied from Perforce
 Change: 179985
 ServerID: perforce.ravenbrook.com
This commit is contained in:
Nick Barnes 2012-10-20 20:34:30 +01:00
parent f0757a1640
commit 1822b23637
1 changed files with 60 additions and 67 deletions
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127
mps/code/eventsql.c
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@ -252,73 +252,6 @@ static void closeDatabase(sqlite3 *db)
log(LOG_SOMETIMES, "Closed %s.", databaseName);
}
/* We need to be able to test for the existence of a table. The
* SQLite3 API seems to have no way to explore metadata like this,
* unless it is compiled in a particular way (in which case the
* function sqlite3_table_column_metadata could be used). Without
* that assistance, we can use a simple SQL trick (which could also
* tell us the number of rows in the table if we cared).
*
* TODO: Update this to use the sqlite_master table:
* SELECT FROM sqlite_master WHERE type='table' AND name=?
* and fix the above comment.
*/
static int tableExists(sqlite3* db, const char *tableName)
{
const char *format = "SELECT SUM(1) FROM %s";
char *sql;
int res;
sql = malloc(strlen(format) + strlen(tableName));
if (!sql)
error("Out of memory.");
sprintf(sql, format, tableName);
log(LOG_SELDOM, "Testing for existence of table '%s' with SQL: %s", tableName, sql);
res = sqlite3_exec(db,
sql,
NULL, /* put in a callback here if we really want to know the number of rows */
NULL, /* callback closure */
NULL); /* error messages handled by sqlite_error */
free(sql);
switch(res) {
case SQLITE_OK:
log(LOG_SELDOM, "Table '%s' exists.", tableName);
return 1; /* table exists */
break;
case SQLITE_ERROR:
log(LOG_SELDOM, "Table '%s' does not exist.", tableName);
return 0; /* table does not exist; we can
probably do a better test for this case. */
break;
default:
sqlite_error(res, db, "Table test failed: %s", tableName);
}
/* UNREACHED */
return 0;
}
/* Unit test for tableExists() */
static const char *tableTests[] = {
"event_kind",
"spong",
"EVENT_SegSplit",
};
static void testTableExists(sqlite3 *db)
{
int i;
for (i=0; i < (sizeof(tableTests)/sizeof(tableTests[0])); ++i) {
if (tableExists(db, tableTests[i]))
printf("Table exists: %s\n", tableTests[i]);
else
printf("Table does not exist: %s\n", tableTests[i]);
}
}
/* Utility functions for SQLite statements. */
static sqlite3_stmt *prepareStatement(sqlite3 *db,
@ -360,6 +293,66 @@ static void runStatement(sqlite3 *db,
sqlite_error(res, db, "%s failed - statement %s", description, sql);
}
/* Test for the existence of a table using sqlite_master table.
*/
static int tableExists(sqlite3* db, const char *tableName)
{
int res;
int exists;
sqlite3_stmt *statement;
statement = prepareStatement(db,
"SELECT 1 FROM sqlite_master WHERE type='table' AND name=?");
res = sqlite3_bind_text(statement, 1, tableName, -1, SQLITE_STATIC);
if (res != SQLITE_OK)
sqlite_error(res, db, "table existence bind of name failed.");
res = sqlite3_step(statement);
switch(res) {
case SQLITE_DONE:
exists = 0;
break;
case SQLITE_ROW:
exists = 1;
break;
default:
sqlite_error(res, db, "select from sqlite_master failed.");
}
finalizeStatement(db, statement);
return exists;
}
/* Unit test for tableExists() */
static struct {
const char* name;
int exists;
} tableTests[] = {
{"event_kind", TRUE},
{"spong", FALSE},
{"EVENT_SegSplit", TRUE}
};
static void testTableExists(sqlite3 *db)
{
int i;
int defects = 0;
int tests = 0;
for (i=0; i < (sizeof(tableTests)/sizeof(tableTests[0])); ++i) {
const char *name = tableTests[i].name;
int exists = tableExists(db, name);
if (exists)
log(LOG_OFTEN, "Table exists: %s", name);
else
log(LOG_OFTEN, "Table does not exist: %s", name);
if (exists != tableTests[i].exists) {
log(LOG_ALWAYS, "tableExists test failed on table %s", name);
++ defects;
}
++ tests;
}
log(LOG_ALWAYS, "%d tests, %d defects found.", tests, defects);
}
/* Every time we put events from a log file into a database file, we
* add the log file to the event_log table, and get a serial number