Set the # of jobs to the # of cores for 'build/test/bench/run -j'.

We do this for 'install -j' already.

cabal-install/Distribution/Client/Install.hs

@@ -134,7 +134,7 @@ import Distribution.Version
 import Distribution.Simple.Utils as Utils
          ( notice, info, warn, debugNoWrap, die, intercalate, withTempDirectory )
 import Distribution.Client.Utils
-         ( numberOfProcessors, inDir, mergeBy, MergeResult(..)
+         ( determineNumJobs, inDir, mergeBy, MergeResult(..)
          , tryCanonicalizePath )
 import Distribution.System
          ( Platform, OS(Windows), buildOS )
@@ -904,10 +904,7 @@ performInstallations verbosity
     platform = InstallPlan.planPlatform installPlan
     compid   = InstallPlan.planCompiler installPlan
 
-    numJobs  = case installNumJobs installFlags of
-      Cabal.NoFlag        -> 1
-      Cabal.Flag Nothing  -> numberOfProcessors
-      Cabal.Flag (Just n) -> n
+    numJobs  = determineNumJobs (installNumJobs installFlags)
     numFetchJobs  = 2
     parallelBuild = numJobs >= 2
 

cabal-install/Distribution/Client/Utils.hs

@@ -2,7 +2,7 @@
 
 module Distribution.Client.Utils ( MergeResult(..)
                                  , mergeBy, duplicates, duplicatesBy
-                                 , inDir, numberOfProcessors
+                                 , inDir, determineNumJobs, numberOfProcessors
                                  , removeExistingFile
                                  , makeAbsoluteToCwd, filePathToByteString
                                  , byteStringToFilePath, tryCanonicalizePath
@@ -10,6 +10,7 @@ module Distribution.Client.Utils ( MergeResult(..)
        where
 
 import Distribution.Compat.Exception ( catchIO )
+import Distribution.Simple.Setup     ( Flag(..) )
 import qualified Data.ByteString.Lazy as BS
 import Control.Monad
          ( when )
@@ -88,6 +89,14 @@ foreign import ccall "getNumberOfProcessors" c_getNumberOfProcessors :: IO CInt
 numberOfProcessors :: Int
 numberOfProcessors = fromEnum $ unsafePerformIO c_getNumberOfProcessors
 
+-- | Determine the number of jobs to use given the value of the '-j' flag.
+determineNumJobs :: Flag (Maybe Int) -> Int
+determineNumJobs numJobsFlag =
+  case numJobsFlag of
+    NoFlag        -> 1
+    Flag Nothing  -> numberOfProcessors
+    Flag (Just n) -> n
+
 -- | Given a relative path, make it absolute relative to the current
 -- directory. Absolute paths are returned unmodified.
 makeAbsoluteToCwd :: FilePath -> IO FilePath

cabal-install/Main.hs

@@ -94,6 +94,7 @@ import Distribution.Client.Sandbox.Timestamp  (maybeAddCompilerTimestampRecord)
 import Distribution.Client.Sandbox.Types      (UseSandbox(..), whenUsingSandbox)
 import Distribution.Client.Init               (initCabal)
 import qualified Distribution.Client.Win32SelfUpgrade as Win32SelfUpgrade
+import Distribution.Client.Utils              (determineNumJobs)
 
 import Distribution.PackageDescription
          ( Executable(..) )
@@ -265,8 +266,12 @@ configureAction (configFlags, configExFlags) extraArgs globalFlags = do
               comp platform conf configFlags'' configExFlags' extraArgs
 
 buildAction :: (BuildFlags, BuildExFlags) -> [String] -> GlobalFlags -> IO ()
-buildAction (buildFlags, buildExFlags) extraArgs globalFlags = do
-  let distPref    = fromFlagOrDefault (useDistPref defaultSetupScriptOptions)
+buildAction (buildFlags', buildExFlags) extraArgs globalFlags = do
+  let buildFlags  = buildFlags' {
+        buildNumJobs = Flag . Just . determineNumJobs . buildNumJobs $
+                       buildFlags'
+        }
+      distPref    = fromFlagOrDefault (useDistPref defaultSetupScriptOptions)
                     (buildDistPref buildFlags)
       verbosity   = fromFlagOrDefault normal (buildVerbosity buildFlags)
       noAddSource = fromFlagOrDefault DontSkipAddSourceDepsCheck
@@ -623,8 +628,12 @@ installAction (configFlags, configExFlags, installFlags, haddockFlags)
 
 testAction :: (TestFlags, BuildFlags, BuildExFlags) -> [String] -> GlobalFlags
               -> IO ()
-testAction (testFlags, buildFlags, buildExFlags) extraArgs globalFlags = do
-  let verbosity      = fromFlagOrDefault normal (testVerbosity testFlags)
+testAction (testFlags, buildFlags', buildExFlags) extraArgs globalFlags = do
+  let buildFlags  = buildFlags' {
+        buildNumJobs = Flag . Just . determineNumJobs . buildNumJobs $
+                       buildFlags'
+        }
+      verbosity      = fromFlagOrDefault normal (testVerbosity testFlags)
       distPref       = fromFlagOrDefault (useDistPref defaultSetupScriptOptions)
                        (testDistPref testFlags)
       setupOptions   = defaultSetupScriptOptions { useDistPref = distPref }
@@ -650,9 +659,13 @@ testAction (testFlags, buildFlags, buildExFlags) extraArgs globalFlags = do
 benchmarkAction :: (BenchmarkFlags, BuildFlags, BuildExFlags)
                    -> [String] -> GlobalFlags
                    -> IO ()
-benchmarkAction (benchmarkFlags, buildFlags, buildExFlags)
+benchmarkAction (benchmarkFlags, buildFlags', buildExFlags)
                 extraArgs globalFlags = do
-  let verbosity      = fromFlagOrDefault normal
+  let buildFlags  = buildFlags' {
+        buildNumJobs = Flag . Just . determineNumJobs . buildNumJobs $
+                       buildFlags'
+        }
+      verbosity      = fromFlagOrDefault normal
                        (benchmarkVerbosity benchmarkFlags)
       distPref       = fromFlagOrDefault (useDistPref defaultSetupScriptOptions)
                        (benchmarkDistPref benchmarkFlags)
@@ -808,8 +821,12 @@ reportAction reportFlags extraArgs globalFlags = do
     (flagToMaybe $ reportPassword reportFlags')
 
 runAction :: (BuildFlags, BuildExFlags) -> [String] -> GlobalFlags -> IO ()
-runAction (buildFlags, buildExFlags) extraArgs globalFlags = do
-  let verbosity   = fromFlagOrDefault normal (buildVerbosity buildFlags)
+runAction (buildFlags', buildExFlags) extraArgs globalFlags = do
+  let buildFlags  = buildFlags' {
+        buildNumJobs = Flag . Just . determineNumJobs . buildNumJobs $
+                       buildFlags'
+        }
+      verbosity   = fromFlagOrDefault normal (buildVerbosity buildFlags)
       distPref    = fromFlagOrDefault (useDistPref defaultSetupScriptOptions)
                     (buildDistPref buildFlags)
       noAddSource = fromFlagOrDefault DontSkipAddSourceDepsCheck