[path_provider_android] Changes internal implementation to use JNI #9770
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This pull request refactors the Android implementation of path_provider to use jnigen and JNI instead of Pigeon for platform communication. This is a significant architectural change. While the implementation looks mostly correct, there are several potential memory leaks due to unreleased JNI objects. I've added specific comments on how to fix them.
A major concern is the removal of all existing tests without adding new ones to cover the new JNI-based implementation. The repository's style guide states that "Code should be tested"[^1]. Given the low-level nature of JNI interop, having a solid test suite is critical to ensure correctness and prevent regressions. Please add tests for the new implementation.
| final JArray<File?>? files = _applicationContext.getExternalCacheDirs(); | ||
| if (files != null) { | ||
| return _toStringList(files); | ||
| } | ||
|
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| return null; |
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The JArray<File?> object returned by getExternalCacheDirs() is a JNI object that needs to be released to avoid a memory leak. The current implementation does not release it.
final JArray<File?>? files = _applicationContext.getExternalCacheDirs();
if (files == null) {
return null;
}
try {
return _toStringList(files);
} finally {
files.release();
}
| final JArray<File?>? files = _applicationContext.getExternalFilesDirs( | ||
| type != null ? _toNativeStorageDirectory(type) : null, | ||
| ); | ||
| if (files != null) { | ||
| return _toStringList(files); | ||
| } | ||
|
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||
| return null; |
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The JArray<File?> object returned by getExternalFilesDirs() is a JNI object that needs to be released to avoid a memory leak. The current implementation does not release it.
final JArray<File?>? files = _applicationContext.getExternalFilesDirs(
type != null ? _toNativeStorageDirectory(type) : null,
);
if (files == null) {
return null;
}
try {
return _toStringList(files);
} finally {
files.release();
}
| final Iterator<File?> filesIterator = files.iterator; | ||
| while (filesIterator.moveNext()) { | ||
| final File? file = filesIterator.current; | ||
| if (file != null) { | ||
| final String? path = | ||
| file.getAbsolutePath()?.toDartString(releaseOriginal: true); | ||
| if (path != null) { | ||
| paths.add(path); | ||
| } | ||
|
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| file.release(); | ||
| } | ||
| } |
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There are two potential memory leaks here:
- The iterator returned by
files.iteratoris aJIterator, which is a JNI object that must be released. - If
file.getAbsolutePath()ortoDartString()throws an exception,file.release()will not be called.
Both can be fixed by using try...finally blocks to ensure release() is always called.
final Iterator<File?> filesIterator = files.iterator;
try {
while (filesIterator.moveNext()) {
final File? file = filesIterator.current;
if (file != null) {
try {
final String? path =
file.getAbsolutePath()?.toDartString(releaseOriginal: true);
if (path != null) {
paths.add(path);
}
} finally {
file.release();
}
}
}
} finally {
(filesIterator as JObject).release();
}
| final File? file = _applicationContext.getCacheDir(); | ||
| final String? path = file?.getPath()?.toDartString(releaseOriginal: true); | ||
| file?.release(); | ||
| return path; |
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To ensure that the File object is always released, even if getPath() or toDartString() throws an exception, it's safer to use a try...finally block.
final File? file = _applicationContext.getCacheDir();
if (file == null) {
return null;
}
try {
return file.getPath()?.toDartString(releaseOriginal: true);
} finally {
file.release();
}
| final File? dir = _applicationContext.getExternalFilesDir(null); | ||
| if (dir != null) { | ||
| final String? path = | ||
| dir.getAbsolutePath()?.toDartString(releaseOriginal: true); | ||
| dir.release(); | ||
| return path; | ||
| } |
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To ensure that the File object (dir) is always released, even if an exception occurs, it's best practice to use a try...finally block.
final File? dir = _applicationContext.getExternalFilesDir(null);
if (dir == null) {
return null;
}
try {
return dir.getAbsolutePath()?.toDartString(releaseOriginal: true);
} finally {
dir.release();
}
Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.
List which issues are fixed by this PR. You must list at least one issue.
Pre-Review Checklist
[shared_preferences]pubspec.yamlwith an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under1.CHANGELOG.mdto add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under1.///).If you need help, consider asking for advice on the #hackers-new channel on Discord.
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