Fix root cause of #1077

When importing lots of keys, lots of messages about the status of keys
is generated, including some debug slime and general fluff that
isn't really needed a lot of the time. As a result, a serious bug can come
along after key imports or certain operations which cause a log to become
parceled.

This commit implements a pool to "dehydrate" logs into: they are placed
into the pool (a ConcurrentHashMap) and a UUID assigned to them, which
is parceled along. When the OperationResult is un-parceled, it reads in
the appropriate UUID bits and rehydrates the appropriate log.

In order to avoid any memory leaks, the log pool removes a reference to
the log itself, allowing the log to die a natural death at the hands
of the GC..

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/results/OperationResult.java

@@ -38,6 +38,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
 
 /** Represent the result of an operation.
  *
@@ -52,6 +54,63 @@ public abstract class OperationResult implements Parcelable {
 
     public static final String EXTRA_RESULT = "operation_result";
 
+
+    /**
+     * A HashMap of UUID:OperationLog which contains logs that we don't need
+     * to care about. This is used such that when we become parceled, we are
+     * well below the 1Mbit boundary that is specified.
+     */
+    private static ConcurrentHashMap<UUID, OperationLog> dehydratedLogs;
+    static {
+        // Static initializer for ConcurrentHashMap
+        dehydratedLogs = new ConcurrentHashMap<UUID,OperationLog>();
+    }
+
+    /**
+     * Dehydrate a log (such that it is available after deparcelization)
+     *
+     * Returns the NULL uuid (0) if you hand it null.
+     * @param log An OperationLog to dehydrate
+     * @return a UUID, the ticket for your dehydrated log
+     *
+     */
+    private static UUID dehydrateLog(OperationLog log) {
+        if(log == null) {
+            return new UUID(0,0);
+        }
+        else {
+            UUID ticket = UUID.randomUUID();
+            dehydratedLogs.put(ticket, log);
+            return ticket;
+        }
+    }
+
+    /***
+     * Rehydrate a log after going through parcelization, invalidating its place in the
+     * dehydration pool.
+     * This is used such that when parcelized, the parcel is no larger than 1mbit.
+     * @param ticket A UUID ticket that identifies the log in question.
+     * @return An OperationLog.
+     */
+    private static OperationLog rehydrateLog(UUID ticket) {
+        if(ticket.getMostSignificantBits() == 0 && ticket.getLeastSignificantBits() == 0) {
+            return null;
+        }
+        else
+        {
+            OperationLog log = dehydratedLogs.get(ticket);
+            invalidateDehydrateTicket(ticket);
+            return log;
+        }
+    }
+    private static void invalidateDehydrateTicket(UUID ticket) {
+        if(ticket.getLeastSignificantBits() != 0 && ticket.getMostSignificantBits() != 0
+                && dehydratedLogs.containsKey(ticket))
+        {
+            dehydratedLogs.remove(ticket);
+        }
+    }
+
     /** Holds the overall result, the number specifying varying degrees of success:
      *  - The first bit is 0 on overall success, 1 on overall failure
      *  - The second bit indicates if the action was cancelled - may still be an error or success!
@@ -65,7 +124,7 @@ public abstract class OperationResult implements Parcelable {
     public static final int RESULT_WARNINGS = 4;
 
     /// A list of log entries tied to the operation result.
-    final OperationLog mLog;
+    protected OperationLog mLog;
 
     public OperationResult(int result, OperationLog log) {
         mResult = result;
@@ -74,8 +133,11 @@ public abstract class OperationResult implements Parcelable {
 
     public OperationResult(Parcel source) {
         mResult = source.readInt();
-        mLog = new OperationLog();
-        mLog.addAll(source.createTypedArrayList(LogEntryParcel.CREATOR));
+        long mostSig = source.readLong();
+        long leastSig = source.readLong();
+        UUID mTicket = new UUID(mostSig, leastSig);
+        // fetch the dehydrated log out of storage (this removes it from the dehydration pool)
+        mLog = rehydrateLog(mTicket);
     }
 
     public int getResult() {
@@ -739,9 +801,11 @@ public abstract class OperationResult implements Parcelable {
     @Override
     public void writeToParcel(Parcel dest, int flags) {
         dest.writeInt(mResult);
-        if (mLog != null) {
-            dest.writeTypedList(mLog.toList());
-        }
+        // Get a ticket for our log.
+        UUID mTicket = dehydrateLog(mLog);
+        // And write out the UUID most and least significant bits.
+        dest.writeLong(mTicket.getMostSignificantBits());
+        dest.writeLong(mTicket.getLeastSignificantBits());
     }
 
     public static class OperationLog implements Iterable<LogEntryParcel> {