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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE FlexibleContexts #-}</span>
<a name="line-3"></a><span class='hs-comment'>-- | Allocate resources from a pool, guaranteeing resource handling via the</span>
<a name="line-4"></a><span class='hs-comment'>-- ResourceT transformer.</span>
<a name="line-5"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Conduit</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span>
<a name="line-6"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>ManagedResource</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-7"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>takeResource</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>takeResourceCheck</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>createPool</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>withResource</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>withResourceTimeout</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>withResourceT</span>
<a name="line-14"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>P</span>
<a name="line-17"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-varid'>liftM</span><span class='hs-layout'>)</span>
<a name="line-18"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Resource</span>
<a name="line-19"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span> <span class='hs-layout'>(</span><span class='hs-varid'>liftIO</span><span class='hs-layout'>)</span>
<a name="line-20"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>I</span>
<a name="line-21"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-layout'>(</span><span class='hs-varid'>onException</span><span class='hs-layout'>,</span> <span class='hs-varid'>mask</span><span class='hs-layout'>)</span>
<a name="line-22"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Timeout</span> <span class='hs-layout'>(</span><span class='hs-varid'>timeout</span><span class='hs-layout'>)</span>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Control</span> <span class='hs-layout'>(</span><span class='hs-varid'>control</span><span class='hs-layout'>)</span>
<a name="line-24"></a>
<a name="line-25"></a><a name="ManagedResource"></a><span class='hs-comment'>-- | The result of taking a resource.</span>
<a name="line-26"></a><a name="ManagedResource"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ManagedResource</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ManagedResource</span>
<a name="line-27"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>mrValue</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ The actual resource.</span>
<a name="line-28"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mrReuse</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-29"></a> <span class='hs-comment'>-- ^ Let's you specify whether the resource should be returned to the pool</span>
<a name="line-30"></a> <span class='hs-comment'>-- (via 'P.putResource') or destroyed (via 'P.destroyResource') on release.</span>
<a name="line-31"></a> <span class='hs-comment'>-- This defaults to destruction, in case of exceptions.</span>
<a name="line-32"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mrRelease</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-33"></a> <span class='hs-comment'>-- ^ Release this resource, either destroying it or returning it to the</span>
<a name="line-34"></a> <span class='hs-comment'>-- pool.</span>
<a name="line-35"></a> <span class='hs-layout'>}</span>
<a name="line-36"></a>
<a name="line-37"></a><a name="withResourceT"></a><span class='hs-comment'>-- | Like 'P.withResource', but uses 'MonadResource' instead of 'MonadBaseControl'.</span>
<a name="line-38"></a><span class='hs-comment'>--</span>
<a name="line-39"></a><span class='hs-comment'>-- Since 0.1.1</span>
<a name="line-40"></a><span class='hs-definition'>withResourceT</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadResource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-41"></a><span class='hs-definition'>withResourceT</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-42"></a> <span class='hs-varid'>mr</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>takeResource</span> <span class='hs-varid'>pool</span>
<a name="line-43"></a> <span class='hs-varid'>b</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>f</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mrValue</span> <span class='hs-varid'>mr</span>
<a name="line-44"></a> <span class='hs-varid'>mrReuse</span> <span class='hs-varid'>mr</span> <span class='hs-conid'>True</span>
<a name="line-45"></a> <span class='hs-varid'>mrRelease</span> <span class='hs-varid'>mr</span>
<a name="line-46"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>b</span>
<a name="line-47"></a>
<a name="line-48"></a><a name="withResourceTimeout"></a><span class='hs-comment'>-- | Like 'P.withResource', but times out the operation if resource</span>
<a name="line-49"></a><span class='hs-comment'>-- allocation does not complete within the given timeout period.</span>
<a name="line-50"></a><span class='hs-comment'>--</span>
<a name="line-51"></a><span class='hs-comment'>-- Since 0.1.2</span>
<a name="line-52"></a><span class='hs-definition'>withResourceTimeout</span> <span class='hs-keyglyph'>::</span>
<a name="line-53"></a><span class='hs-cpp'>#if MIN_VERSION_monad_control(0,3,0)</span>
<a name="line-54"></a> <span class='hs-layout'>(</span><span class='hs-conid'>MonadBaseControl</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-55"></a><span class='hs-cpp'>#else</span>
<a name="line-56"></a> <span class='hs-layout'>(</span><span class='hs-conid'>MonadControlIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-57"></a><span class='hs-cpp'>#endif</span>
<a name="line-58"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ Timeout period in microseconds</span>
<a name="line-59"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span> <span class='hs-varid'>a</span>
<a name="line-60"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-61"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-62"></a><span class='hs-comment'>{-# SPECIALIZE withResourceTimeout :: Int -> P.Pool a -> (a -> IO b) -> IO (Maybe b) #-}</span>
<a name="line-63"></a><span class='hs-definition'>withResourceTimeout</span> <span class='hs-varid'>ms</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>act</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>control</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>runInIO</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>mask</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>restore</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-64"></a> <span class='hs-varid'>mres</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>timeout</span> <span class='hs-varid'>ms</span> <span class='hs-varop'>$</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>takeResource</span> <span class='hs-varid'>pool</span>
<a name="line-65"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>mres</span> <span class='hs-keyword'>of</span>
<a name="line-66"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runInIO</span> <span class='hs-varop'>$</span> <span class='hs-varid'>return</span> <span class='hs-conid'>Nothing</span>
<a name="line-67"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>resource</span><span class='hs-layout'>,</span> <span class='hs-varid'>local</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-68"></a> <span class='hs-varid'>ret</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>restore</span> <span class='hs-layout'>(</span><span class='hs-varid'>runInIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>liftM</span> <span class='hs-conid'>Just</span> <span class='hs-varop'>$</span> <span class='hs-varid'>act</span> <span class='hs-varid'>resource</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varop'>`onException`</span>
<a name="line-69"></a> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>destroyResource</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>local</span> <span class='hs-varid'>resource</span>
<a name="line-70"></a> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>putResource</span> <span class='hs-varid'>local</span> <span class='hs-varid'>resource</span>
<a name="line-71"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>ret</span>
<a name="line-72"></a><span class='hs-cpp'>#if __GLASGOW_HASKELL__ >= 700</span>
<a name="line-73"></a><span class='hs-comment'>{-# INLINABLE withResourceTimeout #-}</span>
<a name="line-74"></a><span class='hs-cpp'>#endif</span>
<a name="line-75"></a>
<a name="line-76"></a><a name="takeResource"></a><span class='hs-comment'>-- | Take a resource from the pool and register a release action.</span>
<a name="line-77"></a><span class='hs-definition'>takeResource</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadResource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ManagedResource</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-78"></a><span class='hs-definition'>takeResource</span> <span class='hs-varid'>pool</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-79"></a> <span class='hs-varid'>onRelRef</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>$</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>newIORef</span> <span class='hs-conid'>False</span>
<a name="line-80"></a> <span class='hs-layout'>(</span><span class='hs-varid'>relKey</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>allocate</span>
<a name="line-81"></a> <span class='hs-layout'>(</span><span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>takeResource</span> <span class='hs-varid'>pool</span><span class='hs-layout'>)</span>
<a name="line-82"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>local</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-83"></a> <span class='hs-varid'>onRel</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>readIORef</span> <span class='hs-varid'>onRelRef</span>
<a name="line-84"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>onRel</span>
<a name="line-85"></a> <span class='hs-keyword'>then</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>putResource</span> <span class='hs-varid'>local</span> <span class='hs-varid'>a</span>
<a name="line-86"></a> <span class='hs-keyword'>else</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>destroyResource</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>local</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-87"></a> <span class='hs-varid'>return</span> <span class='hs-conid'>ManagedResource</span>
<a name="line-88"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>mrValue</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>a</span>
<a name="line-89"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mrReuse</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>.</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>writeIORef</span> <span class='hs-varid'>onRelRef</span>
<a name="line-90"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mrRelease</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>release</span> <span class='hs-varid'>relKey</span>
<a name="line-91"></a> <span class='hs-layout'>}</span>
<a name="line-92"></a>
<a name="line-93"></a><a name="takeResourceCheck"></a><span class='hs-comment'>-- | Same as 'takeResource', but apply some action to check if a resource is</span>
<a name="line-94"></a><span class='hs-comment'>-- still valid.</span>
<a name="line-95"></a><span class='hs-definition'>takeResourceCheck</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadResource</span> <span class='hs-varid'>m</span>
<a name="line-96"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-conid'>Pool</span> <span class='hs-varid'>a</span>
<a name="line-97"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span>
<a name="line-98"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ManagedResource</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-99"></a><span class='hs-definition'>takeResourceCheck</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>check</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-100"></a> <span class='hs-varid'>mr</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>takeResource</span> <span class='hs-varid'>pool</span>
<a name="line-101"></a> <span class='hs-varid'>isValid</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>check</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mrValue</span> <span class='hs-varid'>mr</span>
<a name="line-102"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>isValid</span>
<a name="line-103"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>return</span> <span class='hs-varid'>mr</span>
<a name="line-104"></a> <span class='hs-keyword'>else</span> <span class='hs-keyword'>do</span>
<a name="line-105"></a> <span class='hs-varid'>mrRelease</span> <span class='hs-varid'>mr</span>
<a name="line-106"></a> <span class='hs-varid'>takeResourceCheck</span> <span class='hs-varid'>pool</span> <span class='hs-varid'>check</span>
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