Function RefreshCurrentVersion

pg_documentdb/src/utils/version_utils.c:199–270

static ExtensionVersion
RefreshCurrentVersion(void)
{
	ExtensionVersion currentVersion = { 0 };

	if (unlikely(CurrentVersion == NULL))
	{
		/* Shared memory is not initialized */
		return currentVersion;
	}

	pg_memory_barrier();
	currentVersion = *CurrentVersion;

	if (currentVersion.Major > DocDB_V0 ||
		(currentVersion.Major == DocDB_V0 && currentVersion.Minor > 0))
	{
		return currentVersion;
	}

	/*
	 * Temporarily disable unimportant logs related to version lookup
	 * so that regression test outputs don't become flaky (e.g.: due to commands
	 * being executed locally).
	 */
	int savedGUCLevel = NewGUCNestLevel();
	SetGUCLocally("client_min_messages", "WARNING");

	bool readOnly = true;
	bool isNull = false;

	char *versionString = ExtensionExecuteQueryOnLocalhostViaLibPQ(
		GetVersionRefreshQuery());

	if (strcmp(versionString, "") == 0)
	{
		RollbackGUCChange(savedGUCLevel);
		return currentVersion;
	}

	int nargs = 1;
	Oid argTypes[1] = { TEXTOID };
	Datum argValues[1] = { CStringGetTextDatum(versionString) };
	char *argNulls = NULL;

	/* LibPQ returns an array as a string in the form of {Major,Minor,Hotfix}, so instead
	 * of parsing the string directly, let's use postgres to cast it to an array as a datum
	 * and just use the deconstructed array to get the values out of it. */
	Datum versionDatum = ExtensionExecuteQueryWithArgsViaSPI("SELECT $1::int4[]",
															 nargs, argTypes, argValues,
															 argNulls, readOnly,
															 SPI_OK_SELECT, &isNull);

	ArrayType *arrayValue = DatumGetArrayTypeP(versionDatum);
	RollbackGUCChange(savedGUCLevel);

	Datum *elements = NULL;
	int numElements = 0;