CacheUpdater.h revision c9d32390e59d99c76b79edd247a1127088ce81ec 
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#ifdef HAVE_MS_C_RUNTIME
16#include <direct.h>
17#endif
18
19using namespace android;
20
21/** CacheUpdater
22 *  This is a pure virtual class that declares abstractions of functions useful
23 *  for managing a cache files. This manager is set up to be used in a
24 *  mirror cache where the source tree is duplicated and filled with processed
25 *  images. This class is abstracted to allow for dependency injection during
26 *  unit testing.
27 *  Usage:
28 *      To update/add a file to the cache, call processImage
29 *      To remove a file from the cache, call deleteFile
30 */
31class CacheUpdater {
32public:
33    // Make sure all the directories along this path exist
34    virtual void ensureDirectoriesExist(String8 path) = 0;
35
36    // Delete a file
37    virtual void deleteFile(String8 path) = 0;
38
39    // Process an image from source out to dest
40    virtual void processImage(String8 source, String8 dest) = 0;
41private:
42};
43
44/** SystemCacheUpdater
45 * This is an implementation of the above virtual cache updater specification.
46 * This implementations hits the filesystem to manage a cache and calls out to
47 * the PNG crunching in images.h to process images out to its cache components.
48 */
49class SystemCacheUpdater : public CacheUpdater {
50public:
51    // Constructor to set bundle to pass to preProcessImage
52    SystemCacheUpdater (Bundle* b)
53        : bundle(b) { };
54
55    // Make sure all the directories along this path exist
56    virtual void ensureDirectoriesExist(String8 path)
57    {
58        // Check to see if we're dealing with a fully qualified path
59        String8 existsPath;
60        String8 toCreate;
61        String8 remains;
62        struct stat s;
63
64        // Check optomistically to see if all directories exist.
65        // If something in the path doesn't exist, then walk the path backwards
66        // and find the place to start creating directories forward.
67        if (stat(path.string(),&s) == -1) {
68            // Walk backwards to find place to start creating directories
69            existsPath = path;
70            do {
71                // As we remove the end of existsPath add it to
72                // the string of paths to create.
73                toCreate = existsPath.getPathLeaf().appendPath(toCreate);
74                existsPath = existsPath.getPathDir();
75            } while (stat(existsPath.string(),&s) == -1);
76
77            // Walk forwards and build directories as we go
78            do {
79                // Advance to the next segment of the path
80                existsPath.appendPath(toCreate.walkPath(&remains));
81                toCreate = remains;
82#ifdef HAVE_MS_C_RUNTIME
83                _mkdir(existsPath.string());
84#else
85                mkdir(existsPath.string(), S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP);
86#endif
87            } while (remains.length() > 0);
88        } //if
89    };
90
91    // Delete a file
92    virtual void deleteFile(String8 path)
93    {
94        if (remove(path.string()) != 0)
95            fprintf(stderr,"ERROR DELETING %s\n",path.string());
96    };
97
98    // Process an image from source out to dest
99    virtual void processImage(String8 source, String8 dest)
100    {
101        // Make sure we're trying to write to a directory that is extant
102        ensureDirectoriesExist(dest.getPathDir());
103
104        preProcessImageToCache(bundle, source, dest);
105    };
106private:
107    Bundle* bundle;
108};
109
110#endif // CACHE_UPDATER_H