Upstream //ios/chrome/browser/snapshots

ios/chrome/browser/snapshots/snapshot_cache.mm

Index: ios/chrome/browser/snapshots/snapshot_cache.mm
diff --git a/ios/chrome/browser/snapshots/snapshot_cache.mm b/ios/chrome/browser/snapshots/snapshot_cache.mm
new file mode 100644
index 0000000000000000000000000000000000000000..96fba90b5c8bc9e0f43dad185f851b2d7de89abb
--- /dev/null
+++ b/ios/chrome/browser/snapshots/snapshot_cache.mm
@@ -0,0 +1,466 @@
+// Copyright 2012 The Chromium Authors. All rights reserved.

[Paweł Hajdan Jr., 2015/01/30 12:24:29]

nit: 2015

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/snapshots/snapshot_cache.h"
+
+#import <UIKit/UIKit.h>
+
+#include "base/critical_closure.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/mac/bind_objc_block.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "base/strings/sys_string_conversions.h"
+#include "base/threading/thread_restrictions.h"
+#include "ios/chrome/browser/ui/ui_util.h"
+#import "ios/chrome/browser/ui/uikit_ui_util.h"
+#include "ios/public/consumer/base/util.h"
+#include "ios/web/public/web_thread.h"
+
+namespace {
+static NSArray* const kSnapshotCacheDirectory = @[ @"Chromium", @"Snapshots" ];
+
+const NSUInteger kCacheInitialCapacity = 100;
+const NSUInteger kGreyInitialCapacity = 8;
+const CGFloat kJPEGImageQuality = 1.0;  // Highest quality. No compression.
+// Sequence token to make sure creation/deletion of snapshots don't overlap.
+const char kSequenceToken[] = "SnapshotCacheSequenceToken";
+
+// The paths of the images saved to disk, given a cache directory.
+base::FilePath FilePathForSessionID(NSString* sessionID,
+                                    const base::FilePath& directory) {
+  base::FilePath path = directory.Append(base::SysNSStringToUTF8(sessionID))
+                            .ReplaceExtension(".jpg");
+  if ([SnapshotCache snapshotScaleForDevice] == 2.0) {
+    path = path.InsertBeforeExtension("@2x");
+  } else if ([SnapshotCache snapshotScaleForDevice] == 3.0) {
+    path = path.InsertBeforeExtension("@3x");
+  }
+  return path;
+}
+
+base::FilePath GreyFilePathForSessionID(NSString* sessionID,
+                                        const base::FilePath& directory) {
+  base::FilePath path = directory.Append(base::SysNSStringToUTF8(sessionID) +
+                                         "Grey").ReplaceExtension(".jpg");
+  if ([SnapshotCache snapshotScaleForDevice] == 2.0) {
+    path = path.InsertBeforeExtension("@2x");
+  } else if ([SnapshotCache snapshotScaleForDevice] == 3.0) {
+    path = path.InsertBeforeExtension("@3x");
+  }
+  return path;
+}
+
+UIImage* ReadImageFromDisk(const base::FilePath& filePath) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  // TODO(justincohen): Consider changing this back to -imageWithContentsOfFile
+  // instead of -imageWithData, if the crashing rdar://15747161 is ever fixed.
+  // Tracked in crbug.com/295891.
+  NSString* path = base::SysUTF8ToNSString(filePath.value());
+  return [UIImage imageWithData:[NSData dataWithContentsOfFile:path]
+                          scale:[SnapshotCache snapshotScaleForDevice]];
+}
+
+void WriteImageToDisk(const base::scoped_nsobject<UIImage>& image,
+                      const base::FilePath& filePath) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  if (!image)
+    return;
+  NSString* path = base::SysUTF8ToNSString(filePath.value());
+  [UIImageJPEGRepresentation(image, kJPEGImageQuality) writeToFile:path
+                                                        atomically:YES];
+  // Encrypt the snapshot file (mostly for Incognito, but can't hurt to
+  // always do it).
+  NSDictionary* attributeDict =
+      [NSDictionary dictionaryWithObject:NSFileProtectionComplete
+                                  forKey:NSFileProtectionKey];
+  NSError* error = nil;
+  BOOL success = [[NSFileManager defaultManager] setAttributes:attributeDict
+                                                  ofItemAtPath:path
+                                                         error:&error];
+  if (!success) {
+    DLOG(ERROR) << "Error encrypting thumbnail file"
+                << base::SysNSStringToUTF8([error description]);
+  }
+}
+
+void ConvertAndSaveGreyImage(
+    const base::FilePath& colorPath,
+    const base::FilePath& greyPath,
+    const base::scoped_nsobject<UIImage>& cachedImage) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  base::scoped_nsobject<UIImage> colorImage = cachedImage;
+  if (!colorImage)
+    colorImage.reset([ReadImageFromDisk(colorPath) retain]);
+  if (!colorImage)
+    return;
+  base::scoped_nsobject<UIImage> greyImage([GreyImage(colorImage) retain]);
+  WriteImageToDisk(greyImage, greyPath);
+}
+
+}  // anonymous namespace
+
+@interface SnapshotCache ()
+- (base::FilePath)imagePathForSessionID:(NSString*)sessionID;
+- (base::FilePath)greyImagePathForSessionID:(NSString*)sessionID;
+// Returns the directory where the thumbnails are saved.
+- (base::FilePath)cacheDirectory;
+// Returns the directory where the thumbnails were stored in M28 and earlier.
+- (base::FilePath)oldCacheDirectory;
+// Remove all UIImages from |imageDictionary_|.
+- (void)handleEnterBackground;
+// Remove all but adjacent UIImages from |imageDictionary_|.
+- (void)handleLowMemory;
+// Restore adjacent UIImages to |imageDictionary_|.
+- (void)handleBecomeActive;
+// Clear most recent caller information.
+- (void)clearGreySessionInfo;
+// Load uncached snapshot image and convert image to grey.
+- (void)loadGreyImageAsync:(NSString*)sessionID;
+// Save grey image to |greyImageDictionary_| and call into most recent
+// |mostRecentGreyBlock_| if |mostRecentGreySessionId_| matches |sessionID|.
+- (void)saveGreyImage:(UIImage*)greyImage forKey:(NSString*)sessionID;
+@end
+
+@implementation SnapshotCache
+
+@synthesize pinnedIDs = pinnedIDs_;
+
++ (SnapshotCache*)sharedInstance {
+  static SnapshotCache* instance = [[SnapshotCache alloc] init];
+  return instance;
+}
+
+- (id)init {
+  if ((self = [super init])) {
+    propertyReleaser_SnapshotCache_.Init(self, [SnapshotCache class]);
+
+    // TODO(andybons): In the case where the cache grows, it is expensive.
+    // Make sure this doesn't suck when there are more than ten tabs.
+    imageDictionary_.reset(
+        [[NSMutableDictionary alloc] initWithCapacity:kCacheInitialCapacity]);
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(handleLowMemory)
+               name:UIApplicationDidReceiveMemoryWarningNotification
+             object:nil];
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(handleEnterBackground)
+               name:UIApplicationDidEnterBackgroundNotification
+             object:nil];
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(handleBecomeActive)
+               name:UIApplicationDidBecomeActiveNotification
+             object:nil];
+  }
+  return self;
+}
+
++ (CGFloat)snapshotScaleForDevice {
+  // On handset, the color snapshot is used for the stack view, so the scale of
+  // the snapshot images should match the scale of the device.
+  // On tablet, the color snapshot is only used to generate the grey snapshot,
+  // which does not have to be high quality, so use scale of 1.0 on all tablets.
+  if (IsIPadIdiom()) {
+    return 1.0;
+  }
+  return [UIScreen mainScreen].scale;
+}
+
+- (void)retrieveImageForSessionID:(NSString*)sessionID
+                         callback:(void (^)(UIImage*))callback {
+  DCHECK(sessionID);
+  UIImage* img = [imageDictionary_ objectForKey:sessionID];
+  if (img) {
+    if (callback)
+      callback(img);
+    return;
+  }
+
+  dispatch_queue_t highPriorityQueue =
+      dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
+  DCHECK([NSThread isMainThread]);
+  dispatch_queue_t currentQueue = dispatch_get_main_queue();
+  dispatch_async(highPriorityQueue, ^{
+    // Retrieve the image on a high priority dispatch queue.
+    UIImage* image = ReadImageFromDisk([self imagePathForSessionID:sessionID]);
+    dispatch_async(currentQueue, ^{
+      if (image)
+        [imageDictionary_ setObject:image forKey:sessionID];
+      if (callback)
+        callback(image);
+    });
+  });
+}
+
+- (void)setImage:(UIImage*)img withSessionID:(NSString*)sessionID {
+  if (!img || !sessionID)
+    return;
+
+  // Color snapshots are not used on tablets, so don't keep them in memory.
+  if (!IsIPadIdiom()) {
+    [imageDictionary_ setObject:img forKey:sessionID];
+  }
+  // Save the image to disk.
+  web::WebThread::PostBlockingPoolSequencedTask(
+      kSequenceToken, FROM_HERE,
+      base::BindBlock(^{
+        base::scoped_nsobject<UIImage> image([img retain]);
+        WriteImageToDisk(image, [self imagePathForSessionID:sessionID]);
+      }));
+}
+
+- (void)removeImageWithSessionID:(NSString*)sessionID {
+  [imageDictionary_ removeObjectForKey:sessionID];
+  web::WebThread::PostBlockingPoolSequencedTask(
+      kSequenceToken, FROM_HERE,
+      base::BindBlock(^{
+        base::FilePath imagePath = [self imagePathForSessionID:sessionID];
+        base::DeleteFile(imagePath, false);
+        base::DeleteFile([self greyImagePathForSessionID:sessionID], false);
+      }));
+}
+
+- (base::FilePath)oldCacheDirectory {
+  NSArray* paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
+                                                       NSUserDomainMask, YES);
+  NSString* path = [paths objectAtIndex:0];
+  NSArray* path_components =
+      [NSArray arrayWithObjects:path, kSnapshotCacheDirectory[1], nil];
+  return base::FilePath(
+      base::SysNSStringToUTF8([NSString pathWithComponents:path_components]));
+}
+
+- (base::FilePath)cacheDirectory {
+  NSArray* paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
+                                                       NSUserDomainMask, YES);
+  NSString* path = [paths objectAtIndex:0];
+  NSArray* path_components =
+      [NSArray arrayWithObjects:path, kSnapshotCacheDirectory[0],
+                                kSnapshotCacheDirectory[1], nil];
+  return base::FilePath(
+      base::SysNSStringToUTF8([NSString pathWithComponents:path_components]));
+}
+
+- (base::FilePath)imagePathForSessionID:(NSString*)sessionID {
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  base::FilePath path([self cacheDirectory]);
+
+  BOOL exists = base::PathExists(path);
+  DCHECK(base::DirectoryExists(path) || !exists);
+  if (!exists) {
+    bool result = base::CreateDirectory(path);
+    DCHECK(result);
+  }
+  return FilePathForSessionID(sessionID, path);
+}
+
+- (base::FilePath)greyImagePathForSessionID:(NSString*)sessionID {
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  base::FilePath path([self cacheDirectory]);
+
+  BOOL exists = base::PathExists(path);
+  DCHECK(base::DirectoryExists(path) || !exists);
+  if (!exists) {
+    bool result = base::CreateDirectory(path);
+    DCHECK(result);
+  }
+  return GreyFilePathForSessionID(sessionID, path);
+}
+
+- (void)purgeCacheOlderThan:(const base::Time&)date
+                    keeping:(NSSet*)liveSessionIds {
+  // Copying the date, as the block must copy the value, not the reference.
+  const base::Time dateCopy = date;
+  web::WebThread::PostBlockingPoolSequencedTask(
+      kSequenceToken, FROM_HERE,
+      base::BindBlock(^{
+        std::set<base::FilePath> filesToKeep;
+        for (NSString* sessionID : liveSessionIds) {
+          base::FilePath curImagePath = [self imagePathForSessionID:sessionID];
+          filesToKeep.insert(curImagePath);
+          filesToKeep.insert([self greyImagePathForSessionID:sessionID]);
+        }
+        base::FileEnumerator enumerator([self cacheDirectory], false,
+                                        base::FileEnumerator::FILES);
+        base::FilePath cur_file;
+        while (!(cur_file = enumerator.Next()).value().empty()) {
+          if (cur_file.Extension() != ".jpg")
+            continue;
+          if (filesToKeep.find(cur_file) != filesToKeep.end()) {
+            continue;
+          }
+          base::FileEnumerator::FileInfo fileInfo = enumerator.GetInfo();
+          if (fileInfo.GetLastModifiedTime() > dateCopy) {
+            continue;
+          }
+          base::DeleteFile(cur_file, false);
+        }
+      }));
+}
+
+- (void)willBeSavedGreyWhenBackgrounding:(NSString*)sessionID {
+  if (!sessionID)
+    return;
+  backgroundingImageSessionId_.reset([sessionID copy]);
+  backgroundingColorImage_.reset(
+      [[imageDictionary_ objectForKey:sessionID] retain]);
+}
+
+- (void)handleLowMemory {
+  NSMutableDictionary* dictionary =
+      [[NSMutableDictionary alloc] initWithCapacity:2];
+  for (NSString* sessionID in pinnedIDs_) {
+    UIImage* image = [imageDictionary_ objectForKey:sessionID];
+    if (image)
+      [dictionary setObject:image forKey:sessionID];
+  }
+  imageDictionary_.reset(dictionary);
+}
+
+- (void)handleEnterBackground {
+  [imageDictionary_ removeAllObjects];
+}
+
+- (void)handleBecomeActive {
+  for (NSString* sessionID in pinnedIDs_)
+    [self retrieveImageForSessionID:sessionID callback:nil];
+}
+
+- (void)saveGreyImage:(UIImage*)greyImage forKey:(NSString*)sessionID {
+  if (greyImage)
+    [greyImageDictionary_ setObject:greyImage forKey:sessionID];
+  if ([sessionID isEqualToString:mostRecentGreySessionId_]) {
+    mostRecentGreyBlock_.get()(greyImage);
+    [self clearGreySessionInfo];
+  }
+}
+
+- (void)loadGreyImageAsync:(NSString*)sessionID {
+  dispatch_queue_t priorityQueue =
+      dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
+  DCHECK([NSThread isMainThread]);
+  dispatch_queue_t currentQueue = dispatch_get_main_queue();
+  // Don't call -retrieveImageForSessionID here because it caches the colored
+  // image, which we don't need for the grey image cache. But if the image is
+  // already in the cache, use it.
+  UIImage* img = [imageDictionary_ objectForKey:sessionID];
+  dispatch_async(priorityQueue, ^{
+    // If the image is not in the cache, load it from disk.
+    UIImage* image = img;
+    if (!image)
+      image = ReadImageFromDisk([self imagePathForSessionID:sessionID]);
+    // If the image is not on disk either, give up.
+    if (!image) {
+      dispatch_async(currentQueue, ^{
+        [self saveGreyImage:nil forKey:sessionID];
+      });
+      return;
+    }
+    UIImage* greyImage = GreyImage(image);
+    dispatch_async(currentQueue, ^{
+      [self saveGreyImage:greyImage forKey:sessionID];
+    });
+  });
+}
+
+- (void)createGreyCache:(NSArray*)sessionIDs {
+  greyImageDictionary_.reset(
+      [[NSMutableDictionary alloc] initWithCapacity:kGreyInitialCapacity]);
+  for (NSString* sessionID in sessionIDs)
+    [self loadGreyImageAsync:sessionID];
+}
+
+- (void)removeGreyCache {
+  greyImageDictionary_.reset();
+  [self clearGreySessionInfo];
+}
+
+- (void)clearGreySessionInfo {
+  mostRecentGreySessionId_.reset();
+  mostRecentGreyBlock_.reset();
+}
+
+- (void)greyImageForSessionID:(NSString*)sessionID
+                     callback:(void (^)(UIImage*))callback {
+  DCHECK(greyImageDictionary_);
+  UIImage* image = [greyImageDictionary_ objectForKey:sessionID];
+  if (image) {
+    callback(image);
+    [self clearGreySessionInfo];
+  } else {
+    mostRecentGreySessionId_.reset([sessionID copy]);
+    mostRecentGreyBlock_.reset([callback copy]);
+  }
+}
+
+- (void)retrieveGreyImageForSessionID:(NSString*)sessionID
+                             callback:(void (^)(UIImage*))callback {
+  if (greyImageDictionary_) {
+    UIImage* image = [greyImageDictionary_ objectForKey:sessionID];
+    if (image) {
+      callback(image);
+      return;
+    }
+  }
+
+  dispatch_queue_t highPriorityQueue =
+      dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
+  DCHECK([NSThread isMainThread]);
+  dispatch_queue_t currentQueue = dispatch_get_main_queue();
+  dispatch_async(highPriorityQueue, ^{
+    // Retrieve the image on a high priority dispatch queue.
+    // Loading the file into NSData is more reliable. -imageWithContentsOfFile
+    // would ocassionally claim the image was not a valid jpg.
+    // "ImageIO: <ERROR> JPEGNot a JPEG file: starts with 0xff 0xd9"
+    // See http://stackoverflow.com/questions/5081297/ios-uiimagejpegrepresentation-error-not-a-jpeg-file-starts-with-0xff-0xd9
+    NSData* imageData =
+        [NSData dataWithContentsOfFile:base::SysUTF8ToNSString(
+            [self greyImagePathForSessionID:sessionID].value())];
+    UIImage* image = imageData ? [UIImage imageWithData:imageData] : nil;
+    DCHECK(callback);
+    dispatch_async(currentQueue, ^{
+      if (!image) {
+        [self retrieveImageForSessionID:sessionID
+                               callback:^(UIImage* image) {
+                                 if (callback && image)
+                                   callback(GreyImage(image));
+                               }];
+      } else if (callback) {
+        callback(image);
+      }
+    });
+  });
+}
+
+- (void)saveGreyInBackgroundForSessionID:(NSString*)sessionID {
+  if (!sessionID)
+    return;
+
+  base::FilePath greyImagePath =
+      GreyFilePathForSessionID(sessionID, [self cacheDirectory]);
+  base::FilePath colorImagePath =
+      FilePathForSessionID(sessionID, [self cacheDirectory]);
+
+  // The color image may still be in memory.  Verify the sessionID matches.
+  if (backgroundingColorImage_) {
+    if (![backgroundingImageSessionId_ isEqualToString:sessionID]) {
+      backgroundingColorImage_.reset();
+      backgroundingImageSessionId_.reset();
+    }
+  }
+
+  web::WebThread::PostBlockingPoolTask(
+      FROM_HERE, base::Bind(&ConvertAndSaveGreyImage, colorImagePath,
+                            greyImagePath, backgroundingColorImage_));
+}
+
+@end