not all respond() calls require locking

The UI thread uses respond() to signal user-visibility on each list
item, so we definitely don't want to block the UI thread on those kinds
of respond() calls. Add an options bitfield whose inaugural value is a
bit that hints that the cursor position must be safely moved prior to
respond().

This fixes some big hiccups that result when syncing + scrolling with
the respond CLs yesterday.

Bug: 9032162
Change-Id: I1c927453b9f474c89861a7295de1e318279e3a49

3 files changed, 29 insertions, 2 deletions

diff --git a/src/com/android/mail/content/ThreadSafeCursorWrapper.java b/src/com/android/mail/content/ThreadSafeCursorWrapper.java
index 35ec10370..ed2b3f93a 100644
--- a/src/com/android/mail/content/ThreadSafeCursorWrapper.java
+++ b/src/com/android/mail/content/ThreadSafeCursorWrapper.java
@@ -20,6 +20,7 @@ import android.database.Cursor;
 import android.database.CursorWrapper;
 import android.os.Bundle;
 
+import com.android.mail.providers.UIProvider;
 import com.android.mail.utils.LogTag;
 import com.android.mail.utils.LogUtils;
 
@@ -98,8 +99,13 @@ public class ThreadSafeCursorWrapper extends CursorWrapper {
 
     @Override
     public Bundle respond(Bundle extras) {
-        synchronized (mLock) {
-            moveToCurrent();
+        final int opts = extras.getInt(UIProvider.ConversationCursorCommand.COMMAND_KEY_OPTIONS);
+        if ((opts & UIProvider.ConversationCursorCommand.OPTION_MOVE_POSITION) != 0) {
+            synchronized (mLock) {
+                moveToCurrent();
+                return super.respond(extras);
+            }
+        } else {
             return super.respond(extras);
         }
     }
diff --git a/src/com/android/mail/providers/Conversation.java b/src/com/android/mail/providers/Conversation.java
index c5b4dc9ed..422f76bca 100644
--- a/src/com/android/mail/providers/Conversation.java
+++ b/src/com/android/mail/providers/Conversation.java
@@ -422,6 +422,9 @@ public class Conversation implements Parcelable {
         final String key = UIProvider.ConversationCursorCommand.COMMAND_GET_CONVERSATION_INFO;
         if (sConversationInfoRequest.isEmpty()) {
             sConversationInfoRequest.putBoolean(key, true);
+            sConversationInfoRequest.putInt(
+                    UIProvider.ConversationCursorCommand.COMMAND_KEY_OPTIONS,
+                    UIProvider.ConversationCursorCommand.OPTION_MOVE_POSITION);
         }
         final Bundle response = cursor.respond(sConversationInfoRequest);
         if (response.containsKey(key)) {
@@ -439,6 +442,9 @@ public class Conversation implements Parcelable {
         final String key = UIProvider.ConversationCursorCommand.COMMAND_GET_RAW_FOLDERS;
         if (sRawFoldersRequest.isEmpty()) {
             sRawFoldersRequest.putBoolean(key, true);
+            sRawFoldersRequest.putInt(
+                    UIProvider.ConversationCursorCommand.COMMAND_KEY_OPTIONS,
+                    UIProvider.ConversationCursorCommand.OPTION_MOVE_POSITION);
         }
         final Bundle response = cursor.respond(sRawFoldersRequest);
         if (response.containsKey(key)) {
diff --git a/src/com/android/mail/providers/UIProvider.java b/src/com/android/mail/providers/UIProvider.java
index fe336ae27..8c6ca86bf 100644
--- a/src/com/android/mail/providers/UIProvider.java
+++ b/src/com/android/mail/providers/UIProvider.java
@@ -20,8 +20,10 @@ package com.android.mail.providers;
 import android.content.ContentProvider;
 import android.content.ContentValues;
 import android.content.Context;
+import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.provider.BaseColumns;
 import android.provider.OpenableColumns;
 import android.text.TextUtils;
@@ -1116,6 +1118,19 @@ public class UIProvider {
         public static final String COMMAND_RESPONSE_FAILED = "failed";
 
         /**
+         * Incoming bundles may include this key with an Integer bitfield value. See below for bit
+         * values.
+         */
+        public static final String COMMAND_KEY_OPTIONS = "options";
+
+        /**
+         * Clients must set this bit when the {@link Cursor#respond(Bundle)} call is being used to
+         * fetch a {@link Parcelable}. It serves as a hint that this call requires the cursor
+         * position to first safely be moved.
+         */
+        public static final int OPTION_MOVE_POSITION = 0x01;
+
+        /**
          * This bundle key has a boolean value: true to indicate that this cursor has been shown
          * to the user.
          * <p>