feat(fcm): Implement `sendEach`, `sendEachAsync`, `sendEachForMulticast` and `sendEachForMulticastAsync` #785

Doris-Ge · 2023-03-17T23:21:11Z

Add sendEach, sendEachAsync, sendEachForMulticast and sendEachForMulticastAsync
Deprecate sendAll, sendAllAsync, sendMulticast and sendMulticastAsync

sendEach vs sendAll

sendEach sends one HTTP request to V1 Send endpoint for each
message in the array.
sendAll sends only one HTTP request to V1 Batch Send endpoint
to send all messages in the array.
sendEach calls messagingClient.send to send each message
and constructs a SendResponse with the returned messageId.
If messagingClient.send throws out an exception, sendEach
will catch the exception and also turn it into a SendResponse
with the exception in it.
sendEach calls ApiFutures.allAsList().get() to execute all
messagingClient.send calls asynchronously and wait for all of
them to complete and construct a BatchResponse with all
SendResponses.
Therefore, unlike sendAll, sendEach does not always throw
an error for a total failure. It can also return a BatchResponse
with only errors in it.

sendEachForMulticast calls sendEach under the hood.
sendEachAsync is the async version of sendEach.
sendEachForMulticastAsync is the async version of sendEachForMulticast.

Will send another PR for integration tests

Doris-Ge · 2023-03-17T23:26:00Z

src/main/java/com/google/firebase/messaging/FirebaseMessaging.java

+          List<SendResponse> responses = ApiFutures.allAsList(list).get();
+          return new BatchResponseImpl(responses);
+        } catch (InterruptedException | ExecutionException e) {
+          throw new FirebaseMessagingException(ErrorCode.CANCELLED, SERVICE_ID);


We can discuss what error code we want to throw here.

Also, we can discuss whether we should make an effort to add a unit test for this case

If one message fails to go through would this throw immediately cancelling the rest of the messages?

If one message fails because of FirebaseMesssagingException, then it won't cancel the rest of the messages because the exception will be caught in sendOpForSendResponse.

Based on my read of https://dzone.com/articles/google-guava-%E2%80%93-futures, allAsList is fail-fast.
So if one message fails because the execute() throws an exception other than FirebaseMesssagingException,

protected SendResponse execute() { try { String messageId = messagingClient.send(message, dryRun); return SendResponse.fromMessageId(messageId); } catch (FirebaseMessagingException e) { return SendResponse.fromException(e); } }

then the rest of the messages will be cancelled. I'm not sure in what cases this could happen, but I think it should be a corner case.

I'm going to merge this PR. Let me know if you have any suggested changes for this. I'll fix it in another PR.

…orMulticastAsync `sendEach` vs `sendAll` 1. `sendEach` sends one HTTP request to V1 Send endpoint for each message in the array. `sendAll` sends only one HTTP request to V1 Batch Send endpoint to send all messages in the array. 2. `sendEach` calls `messagingClient.send` to send each message and constructs a `SendResponse` with the returned `messageId`. If `messagingClient.send` throws out an exception, `sendEach` will catch the exception and also turn it into a `SendResponse` with the exception in it. `sendEach` calls `ApiFutures.allAsList().get()` to execute all `messagingClient.send` calls asynchronously and wait for all of them to complete and construct a `BatchResponse` with all `SendResponse`s. Therefore, unlike `sendAll`, `sendEach` does not always throw an error for a total failure. It can also return a `BatchResponse` with only errors in it. `sendEachForMulticast` calls `sendEach` under the hood. `sendEachAsync` is the async version of `sendEach`. `sendEachForMulticastAsync` is the async version of `sendEachForMulticast`.

testSendEach(), testSendFiveHundredWithSendEach(), testSendEachForMulticast()

lahirumaramba

LGTM! Thank you!!

lahirumaramba · 2023-06-02T16:42:04Z

src/main/java/com/google/firebase/messaging/FirebaseMessaging.java

+          List<SendResponse> responses = ApiFutures.allAsList(list).get();
+          return new BatchResponseImpl(responses);
+        } catch (InterruptedException | ExecutionException e) {
+          throw new FirebaseMessagingException(ErrorCode.CANCELLED, SERVICE_ID);


If one message fails to go through would this throw immediately cancelling the rest of the messages?

…st` and `sendEachForMulticastAsync` (#785) (#815) * feat(fcm): Implement `sendEach`, `sendEachAsync`, `sendEachForMulticast` and `sendEachForMulticastAsync` (#785) * Add org.hamcrest as dependency for unit tests * Implement sendEach, sendEachAsync, sendEachForMulticast and sendEachForMulticastAsync `sendEach` vs `sendAll` 1. `sendEach` sends one HTTP request to V1 Send endpoint for each message in the array. `sendAll` sends only one HTTP request to V1 Batch Send endpoint to send all messages in the array. 2. `sendEach` calls `messagingClient.send` to send each message and constructs a `SendResponse` with the returned `messageId`. If `messagingClient.send` throws out an exception, `sendEach` will catch the exception and also turn it into a `SendResponse` with the exception in it. `sendEach` calls `ApiFutures.allAsList().get()` to execute all `messagingClient.send` calls asynchronously and wait for all of them to complete and construct a `BatchResponse` with all `SendResponse`s. Therefore, unlike `sendAll`, `sendEach` does not always throw an error for a total failure. It can also return a `BatchResponse` with only errors in it. `sendEachForMulticast` calls `sendEach` under the hood. `sendEachAsync` is the async version of `sendEach`. `sendEachForMulticastAsync` is the async version of `sendEachForMulticast`. * Add integration tests for batch-send re-implementation: testSendEach(), testSendFiveHundredWithSendEach(), testSendEachForMulticast() * Replace all "-- i.e." in the comments with "meaning that" * Fix the build errors caused by "Line is longer than 100 characters" * Fix the build errors caused by "package does not exist" * Address doc review comments

sarismet · 2023-11-01T12:12:00Z

Hi @lahirumaramba @Doris-Ge,

Could you please tell a little bit why you deprecated sendAll and recommend us to use sendEach instead? What was the motivation behind it. I know sendEach looks more reliable to debug failed attempts, however, even if it can send http requests async meaning that it may perform as good as sendAll, does it require a single thread from the thread-pool and cause more memory-usage, more networking and less available threads in pool? Therefore, the sendAll method looks more efficient to use threads to me. We are sending millions of notifications in a couple of minutes and we consider to lower our memory usage. Thanks in advance.

Doris-Ge · 2023-11-03T20:13:00Z

Hi @sarismet,

On June 20, 2024, we’re reducing the number of Firebase Cloud Messaging (FCM) legacy register APIs and legacy send APIs that provide similar functionality. This step will allow us to provide you with a more consistent experience and align with Google security standards to improve security, reliability and performance.

Because of these API decommissions, some already-deprecated SDKs and features will stop working after June 20, 2024.

Please consult the tables below to find which Firebase Cloud Messaging (FCM) APIs and corresponding services/SDKs/features will be discontinued and replaced with new alternatives.

This is because sendAll calls the FCM Batch send API which is deprecated and will be discontinued on June 20, 2024 whereas sendEach calls the FCM V1 send API that we will continue to support.

even if it can send http requests async meaning that it may perform as good as sendAll, does it require a single thread from the thread-pool and cause more memory-usage, more networking and less available threads in pool?

I'm not sure whether it requires a single thread to send one async request. For lowering memory usage, I'd suggest to reduce the number of messages to send per sendEach call.

amitkumar43 · 2024-01-31T06:31:10Z

Hi @sarismet
What are your learning after moving to sendAll APIs and any optimizations you did for making your system performant at this scale with sendAll APIs.
We are calling sendAll API with a list size of 100, and seeing some gaps around performance.

sarismet · 2024-06-10T10:57:26Z

Hi @amitkumar43

We overwrite ThreadManager with custom thread executor. It helps a lot. Before that our Kafka consumer gets into rebalancing.

Nowadays, we are trying to use virtualThreadExecutors in ThreadManager. We reach 2 millions request per minutes but we got errors saying that "Error writing request body to server", "Remote host terminated the handshake", "Unexpected end of file from server". When load is decreased, the error counts decreases as well.

Do you have any idea what causes these errors? Have you ever tried virtual threads in that project? @Doris-Ge @lahirumaramba

Our java docker image: eclipse-temurin:21.0.3_9-jre-alpine

Add org.hamcrest as dependency for unit tests

e8c4087

Doris-Ge changed the base branch from master to fcm-batch-send March 17, 2023 23:21

Doris-Ge commented Mar 17, 2023

View reviewed changes

Doris-Ge force-pushed the remotes/dorisge/fcm-batch-send branch from 65f4435 to bd798b5 Compare March 17, 2023 23:36

Doris-Ge requested a review from lahirumaramba March 17, 2023 23:40

Add integration tests for batch-send re-implementation:

95556e9

testSendEach(), testSendFiveHundredWithSendEach(), testSendEachForMulticast()

lahirumaramba added release-note release:stage Stage a release candidate labels Jun 1, 2023

lahirumaramba changed the title ~~Implement sendEach, sendEachAsync, sendEachForMulticast and sendEachForMulticastAsync~~ feat(fcm): Implement sendEach, sendEachAsync, sendEachForMulticast and sendEachForMulticastAsync Jun 1, 2023

lahirumaramba removed release-note release:stage Stage a release candidate labels Jun 1, 2023

lahirumaramba approved these changes Jun 2, 2023

View reviewed changes

lahirumaramba assigned Doris-Ge Jun 2, 2023

Doris-Ge merged commit b90979e into fcm-batch-send Jun 2, 2023

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feat(fcm): Implement `sendEach`, `sendEachAsync`, `sendEachForMulticast` and `sendEachForMulticastAsync` #785

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feat(fcm): Implement `sendEach`, `sendEachAsync`, `sendEachForMulticast` and `sendEachForMulticastAsync` #785

feat(fcm): Implement `sendEach`, `sendEachAsync`, `sendEachForMulticast` and `sendEachForMulticastAsync` #785

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