Better FS Locking.

libaxolotl/build.gradle

@@ -1,3 +1,13 @@
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:0.9.+'
+    }
+}
+
 apply plugin: 'android-library'
 
 repositories {

library/src/org/whispersystems/textsecure/push/PreKeyEntity.java

@@ -25,16 +25,17 @@ public class PreKeyEntity implements PreKey {
   @Expose(serialize = false)
   private int         deviceId;
 
+  @Expose(serialize = false)
+  private int         registrationId;
+
   private int         keyId;
   private ECPublicKey publicKey;
   private IdentityKey identityKey;
-  private int         registrationId;
 
   public PreKeyEntity(int keyId, ECPublicKey publicKey, IdentityKey identityKey) {
     this.keyId       = keyId;
     this.publicKey   = publicKey;
     this.identityKey = identityKey;
-    this.registrationId = registrationId;
   }
 
   public int getDeviceId() {

library/src/org/whispersystems/textsecure/storage/TextSecurePreKeyStore.java

@@ -22,6 +22,7 @@ public class TextSecurePreKeyStore implements PreKeyStore {
 
   public  static final String PREKEY_DIRECTORY       = "prekeys";
   private static final int    CURRENT_VERSION_MARKER = 1;
+  private static final Object FILE_LOCK              = new Object();
   private static final String TAG                    = TextSecurePreKeyStore.class.getSimpleName();
 
   private final Context      context;
@@ -34,6 +35,7 @@ public class TextSecurePreKeyStore implements PreKeyStore {
 
   @Override
   public PreKeyRecord load(int preKeyId) throws InvalidKeyIdException {
+    synchronized (FILE_LOCK) {
       try {
         MasterCipher    masterCipher  = new MasterCipher(masterSecret);
         FileInputStream fin           = new FileInputStream(getPreKeyFile(preKeyId));
@@ -51,9 +53,11 @@ public class TextSecurePreKeyStore implements PreKeyStore {
         throw new InvalidKeyIdException(e);
       }
     }
+  }
 
   @Override
   public void store(int preKeyId, PreKeyRecord record) {
+    synchronized (FILE_LOCK) {
       try {
         MasterCipher     masterCipher = new MasterCipher(masterSecret);
         RandomAccessFile recordFile   = new RandomAccessFile(getPreKeyFile(preKeyId), "rw");
@@ -69,6 +73,7 @@ public class TextSecurePreKeyStore implements PreKeyStore {
         throw new AssertionError(e);
       }
     }
+  }
 
   @Override
   public boolean contains(int preKeyId) {

library/src/org/whispersystems/textsecure/storage/TextSecureSessionStore.java

@@ -74,6 +74,7 @@ public class TextSecureSessionStore implements SessionStore {
 
   @Override
   public void store(long recipientId, int deviceId, SessionRecord record) {
+    synchronized (FILE_LOCK) {
       try {
         MasterCipher     masterCipher = new MasterCipher(masterSecret);
         RandomAccessFile sessionFile  = new RandomAccessFile(getSessionFile(recipientId, deviceId), "rw");
@@ -89,6 +90,7 @@ public class TextSecureSessionStore implements SessionStore {
         throw new AssertionError(e);
       }
     }
+  }
 
   @Override
   public boolean contains(long recipientId, int deviceId) {