Try using shasum/awk for comparing hashes of PaketRestoreCacheFile an…

…d PaketLockFilePath for speed boost on osx and linux

src/Paket/embedded/Paket.Restore.targets

@@ -38,9 +38,24 @@
       <NoWarn>$(NoWarn);NU1603</NoWarn>
     </PropertyGroup>
 
+    <!-- Because ReadAllText is slow on osx/linux, try to find shasum and awk -->
+    <PropertyGroup>
+        <PaketRestoreCachedHasher Condition="'$(OS)' != 'Windows_NT' And '$(PaketRestoreCachedHasher)' == '' And Exists('/usr/bin/shasum') And Exists('/usr/bin/awk')">/usr/bin/shasum $(PaketRestoreCacheFile) | /usr/bin/awk '{ print $1 }'</PaketRestoreCachedHasher>
+        <PaketRestoreLockFileHasher Condition="'$(OS)' != 'Windows_NT' And '$(PaketRestoreLockFileHash)' == '' And Exists('/usr/bin/shasum') And Exists('/usr/bin/awk')">/usr/bin/shasum $(PaketLockFilePath) | /usr/bin/awk '{ print $1 }'</PaketRestoreLockFileHasher>
+    </PropertyGroup>
+
+    <!-- If shasum and awk exist get the hashes -->
+    <Exec Condition=" '$(PaketRestoreCachedHasher)' != '' " Command="$(PaketRestoreCachedHasher)" ConsoleToMSBuild='true'>
+        <Output TaskParameter="ConsoleOutput" PropertyName="PaketRestoreCachedHash" />
+    </Exec>
+    <Exec Condition=" '$(PaketRestoreLockFileHasher)' != '' " Command="$(PaketRestoreLockFileHasher)" ConsoleToMSBuild='true'>
+        <Output TaskParameter="ConsoleOutput" PropertyName="PaketRestoreLockFileHash" />
+    </Exec>
+
     <PropertyGroup Condition="Exists('$(PaketRestoreCacheFile)') ">
-      <PaketRestoreCachedHash>$([System.IO.File]::ReadAllText('$(PaketRestoreCacheFile)'))</PaketRestoreCachedHash>
-      <PaketRestoreLockFileHash>$([System.IO.File]::ReadAllText('$(PaketLockFilePath)'))</PaketRestoreLockFileHash>
+      <!-- if no hash has been done yet fall back to just reading in the files and comparing them -->
+      <PaketRestoreCachedHash Condition=" '$(PaketRestoreCachedHash)' == '' ">$([System.IO.File]::ReadAllText('$(PaketRestoreCacheFile)'))</PaketRestoreCachedHash>
+      <PaketRestoreLockFileHash Condition=" '$(PaketRestoreLockFileHash)' == '' ">$([System.IO.File]::ReadAllText('$(PaketLockFilePath)'))</PaketRestoreLockFileHash>
       <PaketRestoreRequired>true</PaketRestoreRequired>
       <PaketRestoreRequired Condition=" '$(PaketRestoreLockFileHash)' == '$(PaketRestoreCachedHash)' ">false</PaketRestoreRequired>
       <PaketRestoreRequired Condition=" '$(PaketRestoreLockFileHash)' == '' ">true</PaketRestoreRequired>