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package com.bumptech.glide.manager;
import com.bumptech.glide.request.Request;
import com.bumptech.glide.util.Util;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.WeakHashMap;
/**
* A class for tracking, canceling, and restarting in progress, completed, and failed requests.
*
* This class is not thread safe and must be accessed on the main thread.
*/
public class RequestTracker {
// Most requests will be for views and will therefore be held strongly (and safely) by the view
// via the tag. However, a user can always pass in a different type of target which may end up not
// being strongly referenced even though the user still would like the request to finish. Weak
// references are therefore only really functional in this context for view targets. Despite the
// side affects, WeakReferences are still essentially required. A user can always make repeated
// requests into targets other than views, or use an activity manager in a fragment pager where
// holding strong references would steadily leak bitmaps and/or views.
private final Set requests =
Collections.newSetFromMap(new WeakHashMap());
// A set of requests that have not completed and are queued to be run again. We use this list to
// maintain hard references to these requests to ensure that they are not garbage collected
// before they start running or while they are paused. See #346.
@SuppressWarnings("MismatchedQueryAndUpdateOfCollection")
private final List pendingRequests = new ArrayList<>();
private boolean isPaused;
/**
* Starts tracking the given request.
*/
public void runRequest(Request request) {
requests.add(request);
if (!isPaused) {
request.begin();
} else {
pendingRequests.add(request);
}
}
// Visible for testing.
void addRequest(Request request) {
requests.add(request);
}
/**
* Stops tracking the given request, clears, and recycles it, and returns {@code true} if the
* request was removed or {@code false} if the request was not found.
*/
public boolean clearRemoveAndRecycle(Request request) {
if (request == null) {
return false;
}
boolean isOwnedByUs = requests.remove(request);
// Avoid short circuiting.
isOwnedByUs = pendingRequests.remove(request) || isOwnedByUs;
if (isOwnedByUs) {
request.clear();
request.recycle();
}
return isOwnedByUs;
}
/**
* Returns {@code true} if requests are currently paused, and {@code false} otherwise.
*/
public boolean isPaused() {
return isPaused;
}
/**
* Stops any in progress requests.
*/
public void pauseRequests() {
isPaused = true;
for (Request request : Util.getSnapshot(requests)) {
if (request.isRunning()) {
request.pause();
pendingRequests.add(request);
}
}
}
/**
* Starts any not yet completed or failed requests.
*/
public void resumeRequests() {
isPaused = false;
for (Request request : Util.getSnapshot(requests)) {
if (!request.isComplete() && !request.isCancelled() && !request.isRunning()) {
request.begin();
}
}
pendingRequests.clear();
}
/**
* Cancels all requests and clears their resources.
*
* After this call requests cannot be restarted.
*/
public void clearRequests() {
for (Request request : Util.getSnapshot(requests)) {
clearRemoveAndRecycle(request);
}
pendingRequests.clear();
}
/**
* Restarts failed requests and cancels and restarts in progress requests.
*/
public void restartRequests() {
for (Request request : Util.getSnapshot(requests)) {
if (!request.isComplete() && !request.isCancelled()) {
// Ensure the request will be restarted in onResume.
request.pause();
if (!isPaused) {
request.begin();
} else {
pendingRequests.add(request);
}
}
}
}
@Override
public String toString() {
return super.toString() + "{numRequests=" + requests.size() + ", isPaused=" + isPaused + "}";
}
}