476112c · typeable/postgresql-simple

git.iko.soy/typeable/postgresql-simple

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Add support for read-only transactions

476112cLeon P Smith15 years ago

src/Database/PostgreSQL/Simple.hs+45−20

compare with master

unifiedsplit

@@ -69,8 +69,8 @@ module Database.PostgreSQL.Simple

69 , query

70 , query_

71 -- * Queries that stream results

72− , FetchQuantity(..)

73 , FoldOptions(..)

72 , FoldOptions(..)

73+ , FetchQuantity(..)

74 , defaultFoldOptions

75 , fold

76 , foldWithOptions

@@ -85,11 +85,13 @@ module Database.PostgreSQL.Simple

85-- , Base.insertID

86 -- * Transaction handling

87 , withTransaction

88− , withTransactionLevel

88+ , TransactionMode(..)

89 , IsolationLevel(..)

90+ , ReadWriteMode(..)

91+ , withTransactionMode

90-- , Base.autocommit

92-- , Base.autocommit

91 , begin

93 , begin

92− , beginLevel

94+ , beginMode

93 , commit

95 , commit

94 , rollback

96 , rollback

95 -- * Helper functions

97 -- * Helper functions

@@ -332,12 +334,14 @@ data FetchQuantity

332

334

333data FoldOptions

335data FoldOptions

334 = FoldOptions {

336 = FoldOptions {

335− fetchQuantity :: !FetchQuantity,

337+ fetchQuantity :: !FetchQuantity,

336− isolationLevel :: !IsolationLevel

338+ transactionMode :: !TransactionMode

337 }

339 }

338

340

339−defaultFoldOptions = FoldOptions { fetchQuantity = Automatic

341+defaultFoldOptions = FoldOptions {

340− , isolationLevel = ReadCommitted }

342+ fetchQuantity = Automatic,

343+ transactionMode = TransactionMode ReadCommitted ReadOnly

344+ }

341

345

342foldWithOptions :: ( QueryResults row, QueryParams params )

346foldWithOptions :: ( QueryResults row, QueryParams params )

343 => FoldOptions

347 => FoldOptions

@@ -382,7 +386,7 @@ doFold :: ( QueryResults row )

382doFold FoldOptions{..} conn _template q a f = do

386doFold FoldOptions{..} conn _template q a f = do

383 stat <- withConnection conn PQ.transactionStatus

387 stat <- withConnection conn PQ.transactionStatus

384 case stat of

388 case stat of

385− PQ.TransIdle -> withTransactionLevel isolationLevel conn go

389+ PQ.TransIdle -> withTransactionMode transactionMode conn go

386 PQ.TransInTrans -> go

390 PQ.TransInTrans -> go

387 PQ.TransActive -> fail "foldWithOpts FIXME: PQ.TransActive"

391 PQ.TransActive -> fail "foldWithOpts FIXME: PQ.TransActive"

388 -- This _shouldn't_ occur in the current incarnation of

392 -- This _shouldn't_ occur in the current incarnation of

@@ -484,6 +488,19 @@ data IsolationLevel

484 | Serializable

488 | Serializable

485 deriving (Show, Eq, Ord, Enum, Bounded)

489 deriving (Show, Eq, Ord, Enum, Bounded)

486

490

491+data ReadWriteMode

492+ = ReadWrite

493+ | ReadOnly

494+ deriving (Show, Eq, Ord, Enum, Bounded)

495+

496+data TransactionMode = TransactionMode {

497+ isolationLevel :: !IsolationLevel,

498+ readWriteMode :: !ReadWriteMode

499+ } deriving (Show, Eq, Ord)

500+

501+defaultTransactionMode :: TransactionMode

502+defaultTransactionMode = TransactionMode ReadCommitted ReadWrite

503+

487-- | Execute an action inside a SQL transaction.

504-- | Execute an action inside a SQL transaction.

488--

505--

489-- This function initiates a transaction with a \"@begin

506-- This function initiates a transaction with a \"@begin

@@ -495,18 +512,17 @@ data IsolationLevel

495-- PostgreSQL-related exception), the transaction will be rolled back using

512-- PostgreSQL-related exception), the transaction will be rolled back using

496-- 'rollback', then the exception will be rethrown.

513-- 'rollback', then the exception will be rethrown.

497withTransaction :: Connection -> IO a -> IO a

514withTransaction :: Connection -> IO a -> IO a

498−withTransaction = withTransactionLevel ReadCommitted

515+withTransaction = withTransactionMode defaultTransactionMode

499

516

500-- | Execute an action inside a SQL transaction with a given isolation level.

517-- | Execute an action inside a SQL transaction with a given isolation level.

501−withTransactionLevel :: IsolationLevel -> Connection -> IO a -> IO a

518+withTransactionMode :: TransactionMode -> Connection -> IO a -> IO a

502−withTransactionLevel isolationLevel conn act = do

519+withTransactionMode mode conn act = do

503− beginLevel isolationLevel conn

520+ beginMode mode conn

504 r <- act `onException` rollback conn

521 r <- act `onException` rollback conn

505 commit conn

522 commit conn

506 return r

523 return r

507

524

508-- | Rollback a transaction.

525-- | Rollback a transaction.

509−-- rollback :: (MonadCatchIO m,MonadIO m) => Connection -> m ()

510rollback :: Connection -> IO ()

526rollback :: Connection -> IO ()

511rollback conn = execute_ conn "ABORT" >> return ()

527rollback conn = execute_ conn "ABORT" >> return ()

512

528

@@ -516,15 +532,24 @@ commit conn = execute_ conn "COMMIT" >> return ()

516

532

517-- | Begin a transaction.

533-- | Begin a transaction.

518begin :: Connection -> IO ()

534begin :: Connection -> IO ()

519−begin = beginLevel ReadCommitted

535+begin = beginMode defaultTransactionMode

520

536

521-- | Begin a transaction with a given isolation level

537-- | Begin a transaction with a given isolation level

522−beginLevel :: IsolationLevel -> Connection -> IO ()

538+beginMode :: TransactionMode -> Connection -> IO ()

523−beginLevel isolationLevel conn = do

539+beginMode mode conn = do

524− execute_ conn $! case isolationLevel of

540+ execute_ conn $! case mode of

541+ TransactionMode ReadCommitted ReadWrite ->

542+ "BEGIN"

525− ReadCommitted -> "BEGIN"

543+ TransactionMode ReadCommitted ReadOnly ->

544+ "BEGIN READ ONLY"

545+ TransactionMode RepeatableRead ReadWrite ->

546+ "BEGIN ISOLATION LEVEL REPEATABLE READ"

547+ TransactionMode RepeatableRead ReadOnly ->

526− RepeatableRead -> "BEGIN ISOLATION LEVEL REPEATABLE READ"

548+ "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"

549+ TransactionMode Serializable ReadWrite ->

550+ "BEGIN ISOLATION LEVEL SERIALIZABLE"

551+ TransactionMode Serializable ReadOnly ->

527− Serializable -> "BEGIN ISOLATION LEVEL SERIALIZABLE"

552+ "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"

528 return ()

553 return ()

529

554

530fmtError :: String -> Query -> [Action] -> a

555fmtError :: String -> Query -> [Action] -> a