com.android.builder.files

Class KeyedFileCache

java.lang.Object

com.android.builder.files.KeyedFileCache

public class KeyedFileCache
extends java.lang.Object

File cache that stored files based on the given key function. The general contract of the KeyedFileCache is that files are stored and can be later retrieved using the file to derive a unique key using the given key function. For example:

 File cacheDir = ... // some directory.
 KeyedFileCache cache = new KeyedFileCache(cacheDir, KeyedFileCache::fileNameKey);

 File a = new File(...); // some file in the filesystem.
 cache.add(a);

 // Modify file "a".
 File b = cache.get(a); // "b" will be a different file whose
                        // contents are those of "a" before
                        // being modified.
 

A custom API for zip files (add(ZipCentralDirectory) allows to only store a zip file's Central Directory Record as this is generally only what is needed from the cache.

Constructor Summary

Constructors

Constructor and Description
KeyedFileCache(java.io.File directory, java.util.function.Function<java.io.File,java.lang.String> keyFunction) Creates a new cache.

Method Summary

Modifier and Type	Method and Description
void	add(java.io.File f) Adds a file to the cache, replacing any file that had the exact same absolute path.
void	add(com.android.builder.files.ZipCentralDirectory centralDirectory) Adds a file to the cache, replacing any file that had the exact same absolute path.
void	clear() Clears the cache.
static java.lang.String	fileNameKey(java.io.File f) Computes a unique key identifying the path of the file.
java.io.File	get(java.io.File f) Obtains the cached file corresponding to the file with the given path.
void	remove(java.io.File f) Removes any cached version of the given path.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

KeyedFileCache

public KeyedFileCache(@NonNull
                      java.io.File directory,
                      @NonNull
                      java.util.function.Function<java.io.File,java.lang.String> keyFunction)

Creates a new cache.

Parameters:

directory - the directory where the cache is stored

keyFunction - a function that maps a file to its location in the cache. See fileNameKey(File) for one example.

Method Detail

add

public void add(@NonNull
                java.io.File f)
         throws java.io.IOException

Adds a file to the cache, replacing any file that had the exact same absolute path.

Parameters:

f - the file to add

Throws:

java.io.IOException - failed to copy the file into the cache

add

public void add(@NonNull
                com.android.builder.files.ZipCentralDirectory centralDirectory)
         throws java.io.IOException

Adds a file to the cache, replacing any file that had the exact same absolute path.

Parameters:

centralDirectory - the file to add

Throws:

java.io.IOException - failed to copy the file into the cache

get

@Nullable
public java.io.File get(@NonNull
                                  java.io.File f)

Obtains the cached file corresponding to the file with the given path.

Parameters:

f - the path

Returns:

the cached file, null if there is no file in the cache that corresponds to the given file

remove

public void remove(@NonNull
                   java.io.File f)
            throws java.io.IOException

Removes any cached version of the given path.

Parameters:

f - the path

Throws:

java.io.IOException - failed to remove the file

fileNameKey

@NonNull
public static java.lang.String fileNameKey(@NonNull
                                                    java.io.File f)

Computes a unique key identifying the path of the file.

WARNING: this is dangerous to use with normalized gradle inputs that discard the absolute path of files.

Parameters:

f - the path

Returns:

the unique key

clear

public void clear()
           throws java.io.IOException

Clears the cache.

Throws:

java.io.IOException - failed to clear the cache