do not attempt to acquire a write lock when resolving so dependencies

Summary: ReentrantReadWriteLocks do not allow promotion of read locks to write lock, causing a deadlock when this is attempted. This changes the logic to only run the source library reparsing when we're at the root level and do not already have the lock. Reviewed By: JamieEi, hick209 Differential Revision: D13581081 fbshipit-source-id: 33432700ac0913365127e540c746ec95a1a7710e
facebook · Jan 4, 2019 · ea661f5 · ea661f5
1 parent ebc9e1e
commit ea661f5
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Showing 3 changed files with 17 additions and 6 deletions.
diff --git a/java/com/facebook/soloader/DirectorySoSource.java b/java/com/facebook/soloader/DirectorySoSource.java
@@ -101,7 +101,9 @@ private void loadDependencies(File soFile, int loadFlags, StrictMode.ThreadPolic
       }
 
       SoLoader.loadLibraryBySoName(
-          dependency, (loadFlags | LOAD_FLAG_ALLOW_IMPLICIT_PROVISION), threadPolicy);
+          dependency,
+          (loadFlags | LOAD_FLAG_ALLOW_IMPLICIT_PROVISION & ~LOAD_FLAG_ALLOW_SOURCE_CHANGE),
+          threadPolicy);
     }
   }
 

diff --git a/java/com/facebook/soloader/SoLoader.java b/java/com/facebook/soloader/SoLoader.java
@@ -499,7 +499,11 @@ public static boolean loadLibrary(String shortName, int loadFlags) throws Unsati
     String soName = mergedLibName != null ? mergedLibName : shortName;
 
     return loadLibraryBySoName(
-        System.mapLibraryName(soName), shortName, mergedLibName, loadFlags, null);
+        System.mapLibraryName(soName),
+        shortName,
+        mergedLibName,
+        loadFlags | SoSource.LOAD_FLAG_ALLOW_SOURCE_CHANGE,
+        null);
   }
 
   /* package */ static void loadLibraryBySoName(
@@ -658,7 +662,9 @@ private static void doLoadLibraryBySoName(
         } finally {
           sSoSourcesLock.readLock().unlock();
         }
-        if (result == SoSource.LOAD_RESULT_NOT_FOUND) {
+        if ((loadFlags & SoSource.LOAD_FLAG_ALLOW_SOURCE_CHANGE)
+                == SoSource.LOAD_FLAG_ALLOW_SOURCE_CHANGE
+            && result == SoSource.LOAD_RESULT_NOT_FOUND) {
           sSoSourcesLock.writeLock().lock();
           try {
             // TODO(T26270128): check and update sBackupSoSource as well

diff --git a/java/com/facebook/soloader/SoSource.java b/java/com/facebook/soloader/SoSource.java
@@ -47,11 +47,14 @@ abstract public class SoSource {
   /** Allow loadLibrary to implicitly provide the library instead of actually loading it. */
   public static final int LOAD_FLAG_ALLOW_IMPLICIT_PROVISION = 1;
 
+  /** Allow loadLibrary to reparse the so sources directories. */
+  public static final int LOAD_FLAG_ALLOW_SOURCE_CHANGE = 1 << 1;
+
   /**
-   * Min flag that can be used in customized {@link SoFileLoader#load(String, int)}
-   * implementation. The custom flag value has to be greater than this.
+   * Min flag that can be used in customized {@link SoFileLoader#load(String, int)} implementation.
+   * The custom flag value has to be greater than this.
    */
-  public static final int LOAD_FLAG_MIN_CUSTOM_FLAG = 1 << 1;
+  public static final int LOAD_FLAG_MIN_CUSTOM_FLAG = LOAD_FLAG_ALLOW_SOURCE_CHANGE << 1;
 
   /**
    * Allow prepare to spawn threads to do background work.