CacheUpdater.h

   1 //
   2 // Copyright 2011 The Android Open Source Project
   3 //
   4 // Abstraction of calls to system to make directories and delete files and
   5 // wrapper to image processing.
   6
   7 #ifndef CACHE_UPDATER_H
   8 #define CACHE_UPDATER_H
   9
  10 #include <utils/String8.h>
  11 #include <sys/types.h>
  12 #include <sys/stat.h>
  13 #include <stdio.h>
  14 #include "Images.h"
  15
  16 using namespace android;
  17
  18 /** CacheUpdater
  19  *  This is a pure virtual class that declares abstractions of functions useful
  20  *  for managing a cache files. This manager is set up to be used in a
  21  *  mirror cache where the source tree is duplicated and filled with processed
  22  *  images. This class is abstracted to allow for dependency injection during
  23  *  unit testing.
  24  *  Usage:
  25  *      To update/add a file to the cache, call processImage
  26  *      To remove a file from the cache, call deleteFile
  27  */
  28 class CacheUpdater {
  29 public:
  30     // Make sure all the directories along this path exist
  31     virtual void ensureDirectoriesExist(String8 path) = 0;
  32
  33     // Delete a file
  34     virtual void deleteFile(String8 path) = 0;
  35
  36     // Process an image from source out to dest
  37     virtual void processImage(String8 source, String8 dest) = 0;
  38 private:
  39 };
  40
  41 /** SystemCacheUpdater
  42  * This is an implementation of the above virtual cache updater specification.
  43  * This implementations hits the filesystem to manage a cache and calls out to
  44  * the PNG crunching in images.h to process images out to its cache components.
  45  */
  46 class SystemCacheUpdater : public CacheUpdater {
  47 public:
  48     // Constructor to set bundle to pass to preProcessImage
  49     SystemCacheUpdater (Bundle* b)
  50         : bundle(b) { };
  51
  52     // Make sure all the directories along this path exist
  53     virtual void ensureDirectoriesExist(String8 path)
  54     {
  55         // Check to see if we're dealing with a fully qualified path
  56         String8 existsPath;
  57         String8 toCreate;
  58         String8 remains;
  59         struct stat s;
  60
  61         // Check optomistically to see if all directories exist.
  62         // If something in the path doesn't exist, then walk the path backwards
  63         // and find the place to start creating directories forward.
  64         if (stat(path.string(),&s) == -1) {
  65             // Walk backwards to find place to start creating directories
  66             existsPath = path;
  67             do {
  68                 // As we remove the end of existsPath add it to
  69                 // the string of paths to create.
  70                 toCreate = existsPath.getPathLeaf().appendPath(toCreate);
  71                 existsPath = existsPath.getPathDir();
  72             } while (stat(existsPath.string(),&s) == -1);
  73
  74             // Walk forwards and build directories as we go
  75             do {
  76                 // Advance to the next segment of the path
  77                 existsPath.appendPath(toCreate.walkPath(&remains));
  78                 toCreate = remains;
  79 #ifdef HAVE_MS_C_RUNTIME
  80                 _mkdir(existsPath.string());
  81 #else
  82                 mkdir(existsPath.string(), S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP);
  83 #endif
  84             } while (remains.length() > 0);
  85         } //if
  86     };
  87
  88     // Delete a file
  89     virtual void deleteFile(String8 path)
  90     {
  91         if (remove(path.string()) != 0)
  92             fprintf(stderr,"ERROR DELETING %s\n",path.string());
  93     };
  94
  95     // Process an image from source out to dest
  96     virtual void processImage(String8 source, String8 dest)
  97     {
  98         // Make sure we're trying to write to a directory that is extant
  99         ensureDirectoriesExist(dest.getPathDir());
 100
 101         preProcessImageToCache(bundle, source, dest);
 102     };
 103 private:
 104     Bundle* bundle;
 105 };
 106
 107 #endif // CACHE_UPDATER_H