From 940a0da1da7378e7f9bf603a11d55eb984f5c427 Mon Sep 17 00:00:00 2001 From: Hari Babu Date: Thu, 21 Feb 2019 23:11:55 +1100 Subject: [PATCH 1/8] Restructure the code to remove duplicate code The duplicate code logic of checking for the server version before issuing the SHOW transaction_read_only to find out whether the server is read-write or not is restructured under a new connection status, so that duplicate code is removed. This is required for the next set of patches --- doc/src/sgml/libpq.sgml | 26 +++++--- src/interfaces/libpq/fe-connect.c | 99 ++++++++++++------------------- src/interfaces/libpq/libpq-fe.h | 3 +- 3 files changed, 57 insertions(+), 71 deletions(-) diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml index fe833aa626..67e81e98e1 100644 --- a/doc/src/sgml/libpq.sgml +++ b/doc/src/sgml/libpq.sgml @@ -1647,17 +1647,27 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname target_session_attrs + + The supported options for this parameter are, any and + read-write. The default value of this parameter, + any, regards all connections as acceptable. + If multiple hosts were specified in the connection string, based on the + specified value, any remaining servers will be tried before confirming + succesful connection or failure. + + If this parameter is set to read-write, only a connection in which read-write transactions are accepted by default - is considered acceptable. The query - SHOW transaction_read_only will be sent upon any - successful connection; if it returns on, the connection - will be closed. If multiple hosts were specified in the connection - string, any remaining servers will be tried just as if the connection - attempt had failed. The default value of this parameter, - any, regards all connections as acceptable. - + is considered acceptable. + + + + To find out whether the server supports read-write transactions are not, + query SHOW transaction_read_only will be sent upon any + successful connection; if it returns on, it means server + doesn't support read-write transactions. + diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index 87df79880a..9bb2e9631f 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -3434,6 +3434,43 @@ keep_going: /* We will come back to here until there is return PGRES_POLLING_WRITING; } + conn->status = CONNECTION_CHECK_TARGET; + goto keep_going; + } + + case CONNECTION_SETENV: + { + + /* + * Do post-connection housekeeping (only needed in protocol 2.0). + * + * We pretend that the connection is OK for the duration of these + * queries. + */ + conn->status = CONNECTION_OK; + + switch (pqSetenvPoll(conn)) + { + case PGRES_POLLING_OK: /* Success */ + break; + + case PGRES_POLLING_READING: /* Still going */ + conn->status = CONNECTION_SETENV; + return PGRES_POLLING_READING; + + case PGRES_POLLING_WRITING: /* Still going */ + conn->status = CONNECTION_SETENV; + return PGRES_POLLING_WRITING; + + default: + goto error_return; + } + } + + /* Intentional fall through */ + + case CONNECTION_CHECK_TARGET: + { /* * If a read-write connection is required, see if we have one. * @@ -3475,68 +3512,6 @@ keep_going: /* We will come back to here until there is return PGRES_POLLING_OK; } - case CONNECTION_SETENV: - - /* - * Do post-connection housekeeping (only needed in protocol 2.0). - * - * We pretend that the connection is OK for the duration of these - * queries. - */ - conn->status = CONNECTION_OK; - - switch (pqSetenvPoll(conn)) - { - case PGRES_POLLING_OK: /* Success */ - break; - - case PGRES_POLLING_READING: /* Still going */ - conn->status = CONNECTION_SETENV; - return PGRES_POLLING_READING; - - case PGRES_POLLING_WRITING: /* Still going */ - conn->status = CONNECTION_SETENV; - return PGRES_POLLING_WRITING; - - default: - goto error_return; - } - - /* - * If a read-write connection is required, see if we have one. - * (This should match the stanza in the CONNECTION_AUTH_OK case - * above.) - * - * Servers before 7.4 lack the transaction_read_only GUC, but by - * the same token they don't have any read-only mode, so we may - * just skip the test in that case. - */ - if (conn->sversion >= 70400 && - conn->target_session_attrs != NULL && - strcmp(conn->target_session_attrs, "read-write") == 0) - { - if (!saveErrorMessage(conn, &savedMessage)) - goto error_return; - - conn->status = CONNECTION_OK; - if (!PQsendQuery(conn, - "SHOW transaction_read_only")) - { - restoreErrorMessage(conn, &savedMessage); - goto error_return; - } - conn->status = CONNECTION_CHECK_WRITABLE; - restoreErrorMessage(conn, &savedMessage); - return PGRES_POLLING_READING; - } - - /* We can release the address list now. */ - release_conn_addrinfo(conn); - - /* We are open for business! */ - conn->status = CONNECTION_OK; - return PGRES_POLLING_OK; - case CONNECTION_CONSUME: { conn->status = CONNECTION_OK; diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h index f44030b4b0..39579cd040 100644 --- a/src/interfaces/libpq/libpq-fe.h +++ b/src/interfaces/libpq/libpq-fe.h @@ -67,7 +67,8 @@ typedef enum * connection. */ CONNECTION_CONSUME, /* Wait for any pending message and consume * them. */ - CONNECTION_GSS_STARTUP /* Negotiating GSSAPI. */ + CONNECTION_GSS_STARTUP, /* Negotiating GSSAPI. */ + CONNECTION_CHECK_TARGET /* Check if we have a proper target connection */ } ConnStatusType; typedef enum -- 2.20.1.windows.1