| Copyright | (c) Alexey Radkov 2018 |
|---|---|
| License | BSD-style |
| Maintainer | alexey.radkov@gmail.com |
| Stability | experimental |
| Portability | non-portable (requires Template Haskell) |
| Safe Haskell | None |
| Language | Haskell98 |
NgxExport.Tools
Contents
Description
Extra tools for using in custom Haskell code with nginx-haskell-module.
Synopsis
- exitWorkerProcess :: IO ()
- terminateWorkerProcess :: IO ()
- ngxNow :: IO CTime
- threadDelaySec :: Int -> IO ()
- data TimeInterval
- toSec :: TimeInterval -> Int
- data ServiceMode
- ngxExportSimpleService :: Name -> ServiceMode -> Q [Dec]
- ngxExportSimpleServiceTyped :: Name -> Name -> ServiceMode -> Q [Dec]
- ngxExportSimpleServiceTypedAsJSON :: Name -> Name -> ServiceMode -> Q [Dec]
- newtype CInt = CInt Int32
- newtype CUInt = CUInt Word32
Various useful functions and data
exitWorkerProcess :: IO () Source #
Terminates current Nginx worker process.
Nginx master process shall spawn a new worker process thereafter.
terminateWorkerProcess :: IO () Source #
Terminates current Nginx worker process.
Nginx master process shall not spawn a new worker process thereafter.
Returns current time as the number of seconds elapsed since UNIX epoch.
The value is taken from Nginx core, so no additional system calls get
involved. On the other hand, it means that this is only safe to use from
an Nginx worker's main thread, i.e. in synchronous Haskell handlers and
service hooks. Be also aware that this is a small type casting hack:
the value is interpreted as being of type time_t while having been
actually wrapped in a bigger C struct as its first element.
threadDelaySec :: Int -> IO () Source #
Delays current thread for the specified number of seconds.
data TimeInterval Source #
Time intervals.
Constructors
| Hr Int | Hours |
| Min Int | Minutes |
| Sec Int | Seconds |
| HrMin Int Int | Hours and minutes |
| MinSec Int Int | Minutes and seconds |
Instances
toSec :: TimeInterval -> Int Source #
Converts a time interval into seconds.
Exporters of simple services
There are a number of exporters for simple services. Here simplicity means avoiding boilerplate code regarding to efficient reading of typed configurations and timed restarts of services. All simple services have type
ByteString->Bool->IOByteString
which corresponds to the type of usual services from module NgxExport.
Below is a toy example.
File test_tools.hs.
{-# LANGUAGE TemplateHaskell, DeriveGeneric #-}
module TestTools where
import NgxExport.Tools
import Data.ByteString (ByteString)
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Lazy.Char8 as C8L
import Data.Aeson
import GHC.Generics
test :: ByteString -> Bool -> IO L.ByteString
test = const . return . L.fromStrict
ngxExportSimpleService 'test $
PersistentService $ Just $ Sec 10
newtype ConfRead = ConfRead Int deriving (Read, Show)
testRead :: ConfRead -> Bool -> IO L.ByteString
testRead c = const $ return $ C8L.pack $ show c
ngxExportSimpleServiceTyped 'testRead ''ConfRead $
PersistentService $ Just $ Sec 10
data ConfReadJSON = ConfReadJSONCon1 Int
| ConfReadJSONCon2 deriving (Generic, Show)
instance FromJSON ConfReadJSON
testReadJSON :: ConfReadJSON -> Bool -> IO L.ByteString
testReadJSON c = const $ return $ C8L.pack $ show c
ngxExportSimpleServiceTypedAsJSON 'testReadJSON ''ConfReadJSON
SingleShotService
Here three simple services of various types are defined: test, testRead,
and testReadJSON. As soon as they merely echo their arguments into their
service variables, they must sleep for a while between iterations. Sleeps
are managed by strategies defined in type ServiceMode. There are basically
three sleeping strategies:
- Periodical sleeps (for example,
PersistentService$ Just $Sec10 - No sleeps between iterations (
PersistentServiceNothing - Single-shot services (
SingleShotService
In this toy example the most efficient sleeping strategy is a single-shot
service because data is not altered during runtime. Under the hood, the
single-shot strategy is implemented as periodical sleeps (with period of
Hr 1
All three services ignore their second parameter (of type Bool)
denoting the first run of the service.
File nginx.conf.
user nobody;
worker_processes 2;
events {
worker_connections 1024;
}
http {
default_type application/octet-stream;
sendfile on;
haskell load /var/lib/nginx/test_tools.so;
haskell_run_service simpleService_test $hs_test
test;
haskell_run_service simpleService_testRead $hs_testRead
'ConfRead 20';
haskell_run_service simpleService_testReadJSON $hs_testReadJSON
'{"tag":"ConfReadJSONCon1", "contents":56}';
haskell_service_var_ignore_empty $hs_testReadJSON;
server {
listen 8010;
server_name main;
error_log /tmp/nginx-test-haskell-error.log;
access_log /tmp/nginx-test-haskell-access.log;
location / {
echo "Service variables:";
echo " hs_test: $hs_test";
echo " hs_testRead: $hs_testRead";
echo " hs_testReadJSON: $hs_testReadJSON";
}
}
}
Notice that Haskel handlers defined in test_tools.hs are referred from the Nginx configuration file with prefix simpleService_.
Let's run a simple test.
$ curl 'http://localhost:8010/' Service variables: hs_test: test hs_testRead: ConfRead 20 hs_testReadJSON: ConfReadJSONCon1 56
data ServiceMode Source #
Defines a sleeping strategy.
Single-shot services should be accompanied by Nginx directive haskell_service_var_ignore_empty.
Constructors
| PersistentService (Maybe TimeInterval) | Persistent service (with or without periodical sleeps) |
| SingleShotService | Single-shot service |
ngxExportSimpleService Source #
Arguments
| :: Name | Name of the service |
| -> ServiceMode | Service mode |
| -> Q [Dec] |
Exports a simple service with specified name and service mode.
The service expects a plain ByteString as its first argument.
ngxExportSimpleServiceTyped Source #
Arguments
| :: Name | Name of the service |
| -> Name | Name of the custom type |
| -> ServiceMode | Service mode |
| -> Q [Dec] |
Exports a simple service with specified name and service mode.
The service expects a custom type deriving Read as its first argument.
For the sake of efficiency, the object of this custom type gets deserialized
into a global IORef data storage on the first service run to be further
accessed directly from the storage.
ngxExportSimpleServiceTypedAsJSON Source #
Arguments
| :: Name | Name of the service |
| -> Name | Name of the custom type |
| -> ServiceMode | Service mode |
| -> Q [Dec] |
Exports a simple service with specified name and service mode.
The service expects a custom type deriving FromJSON as its first argument.
For the sake of efficiency, the object of this custom type gets deserialized
into a global IORef data storage on the first service run to be further
accessed directly from the storage.
Re-exported data constructors from Foreign.C
Haskell type representing the C int type.
Instances
| Bounded CInt | |
| Enum CInt | |
| Eq CInt | |
| Integral CInt | |
| Num CInt | |
| Ord CInt | |
| Read CInt | |
| Real CInt | |
Defined in Foreign.C.Types Methods toRational :: CInt -> Rational # | |
| Show CInt | |
| Storable CInt | |
Defined in Foreign.C.Types | |
| Bits CInt | |
Defined in Foreign.C.Types Methods (.&.) :: CInt -> CInt -> CInt # (.|.) :: CInt -> CInt -> CInt # complement :: CInt -> CInt # shift :: CInt -> Int -> CInt # rotate :: CInt -> Int -> CInt # setBit :: CInt -> Int -> CInt # clearBit :: CInt -> Int -> CInt # complementBit :: CInt -> Int -> CInt # testBit :: CInt -> Int -> Bool # bitSizeMaybe :: CInt -> Maybe Int # shiftL :: CInt -> Int -> CInt # unsafeShiftL :: CInt -> Int -> CInt # shiftR :: CInt -> Int -> CInt # unsafeShiftR :: CInt -> Int -> CInt # rotateL :: CInt -> Int -> CInt # | |
| FiniteBits CInt | |
Defined in Foreign.C.Types Methods finiteBitSize :: CInt -> Int # countLeadingZeros :: CInt -> Int # countTrailingZeros :: CInt -> Int # | |
Haskell type representing the C unsigned int type.
Instances
| Bounded CUInt | |
| Enum CUInt | |
Defined in Foreign.C.Types | |
| Eq CUInt | |
| Integral CUInt | |
| Num CUInt | |
| Ord CUInt | |
| Read CUInt | |
| Real CUInt | |
Defined in Foreign.C.Types Methods toRational :: CUInt -> Rational # | |
| Show CUInt | |
| Storable CUInt | |
| Bits CUInt | |
Defined in Foreign.C.Types Methods (.&.) :: CUInt -> CUInt -> CUInt # (.|.) :: CUInt -> CUInt -> CUInt # xor :: CUInt -> CUInt -> CUInt # complement :: CUInt -> CUInt # shift :: CUInt -> Int -> CUInt # rotate :: CUInt -> Int -> CUInt # setBit :: CUInt -> Int -> CUInt # clearBit :: CUInt -> Int -> CUInt # complementBit :: CUInt -> Int -> CUInt # testBit :: CUInt -> Int -> Bool # bitSizeMaybe :: CUInt -> Maybe Int # shiftL :: CUInt -> Int -> CUInt # unsafeShiftL :: CUInt -> Int -> CUInt # shiftR :: CUInt -> Int -> CUInt # unsafeShiftR :: CUInt -> Int -> CUInt # rotateL :: CUInt -> Int -> CUInt # | |
| FiniteBits CUInt | |
Defined in Foreign.C.Types Methods finiteBitSize :: CUInt -> Int # countLeadingZeros :: CUInt -> Int # countTrailingZeros :: CUInt -> Int # | |