deps: update grpc to 1.78.1

[santigimeno]

Summary by CodeRabbit

• New Features

  • Added configurable maximum connections per subchannel for improved connection scaling
  • Enhanced keepalive throttling and propagation across subchannels
  • Expanded channelz diagnostics to include per-filter and per-call properties
  • Improved HTTP/2 protocol compliance with stricter frame and header validation

• Bug Fixes

  • Fixed keepalive time management and synchronization
  • Improved connection state handling and error propagation

• Version Updates

  • Updated gRPC C++ version to 1.78.1
  • Updated core version to 52.0.0

[coderabbitai]

Caution

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Walkthrough

Updates vendored gRPC to C/CPP 52.0.0/1.78.1, introducing allocator-aware message serialization, client/channel refactors (buffered calls, connection-scaling cap, keepalive throttling), expanded Channelz (call-level properties), significant HTTP/2 transport changes (GOAWAY manager, flow-control and settings notification interface), Chaotic Good transport watcher/telemetry updates, credentials HTTP token-fetcher refactor, and build/config tweaks.

Changes

Allocator-Aware Serialization and API Surface

Layer / File(s)	Summary
Data Shape include/grpcpp/impl/serialization_traits.h, include/grpcpp/support/proto_buffer_writer.h, include/grpcpp/impl/generic_serialize.h	Adds allocator-dispatch for serialization; ProtoBufferWriter and GenericSerialize accept optional MemoryAllocator*.
Core Implementation include/grpcpp/impl/call_op_set.h	SendMessage/SendMessagePtr accept allocator and use grpc::Serialize(allocator, ...); recv uses grpc::Deserialize(...).
Wiring (Client) include/grpcpp/impl/client_unary_call.h, include/grrcpp/support/async_*, include/grpcpp/support/client_callback.h, include/grpcpp/support/sync_stream.h	All client send paths pass channel->memory_allocator() to send ops.
Wiring (Server) include/grpcpp/impl/server_callback_handlers.h, include/grpcpp/support/method_handler.h, include/grpcpp/support/async_unary_call.h, include/grpcpp/support/async_stream.h	Server send paths pass ctx_->memory_allocator(); request deserialization switched to grpc::Deserialize.
Interface Additions include/grpcpp/impl/channel_interface.h, include/grpcpp/channel.h, include/grpcpp/impl/delegating_channel.h, include/grpcpp/impl/intercepted_channel.h, include/grpcpp/server.h, include/grpcpp/server_context.h	Adds memory_allocator() to channels/servers; context stores and exposes allocator.
Headers/Deps include/grpc/event_engine/memory_allocator.h, include/grpc/event_engine/memory_request.h	Adds MemoryAllocator::IsValid() and minor include.
Build/Export Makefile, include/grpcpp/version_info.h	CPP version to 1.78.1; new public headers wired.

Client Channel: Buffered Calls, Connection Scaling, Keepalive

Layer / File(s)	Summary
Data Shape include/grpc/impl/channel_arg_names.h, src/core/client_channel/client_channel_internal.h, src/core/client_channel/client_channel_service_config.h	Adds service-config “connection_scaling” and arg keys for max connections per subchannel and cap.
Core Implementation src/core/client_channel/buffered_call.{h,cc}, src/core/client_channel/client_channel_filter.{h,cc}	Introduces BufferedCall and refactors call flow to enqueue/fail/resume batches; unifies LoadBalancedCall; integrates max-connections-per-subchannel and keepalive throttling propagation.
Subchannel/Connector src/core/client_channel/subchannel.{h,cc}, src/core/client_channel/connector.h	Watcher interface gains keepalive and connection-limit hooks; transport watcher path; connector result adds max_concurrent_streams.
Config Parsing src/core/client_channel/client_channel_service_config.{h,cc}	Parses gated connection_scaling.maxConnectionsPerSubchannel.
Wiring/Maps src/core/client_channel/client_channel.{h,cc}	Replaces refcount maps with subchannel→wrapper sets; computes per-subchannel connection max with cap; Duration-based keepalive storage.
Retry Integration src/core/client_channel/retry_filter_*	Switches to new LoadBalancedCall type throughout.
Build Makefile, grpc.gyp	Adds buffered_call.cc to builds.

HTTP/2 Transport and Settings/GOAWAY/Flow-Control

Layer / File(s)	Summary
Data Shape src/core/ext/transport/chttp2/transport/frame.h, flow_control.h, flow_control_manager.h, header_assembler.h	Expands frame/flag types, adds debugging strings, test-only accessors, helpers for dequeue/tokens, header assembler initialization API.
Core Implementation transport/frame.cc, flow_control.cc, header_assembler.h	Adds detailed frame tracing, stricter validations, gRPC header flag parsing, flow-control diagnostics, new header assembler/disassembler flows.
GOAWAY Manager transport/goaway.{h,cc}	Introduces stateful GOAWAY manager with graceful/immediate flows and serialization hooks.
Settings Notification API transport/chttp2_transport.{h,cc}, client/chttp2_connector.{h,cc}, server/chttp2_server.{h,cc}	Replaces grpc_closure* with absl::AnyInvocable<StatusOr<uint32_t>>; updates client/server handshake paths; adds watcher notifications for disconnect and peer max streams.
Telemetry/Writes transport/chttp2_transport.cc, .../data_endpoints.cc	Enables TCP telemetry when plugin group available; extends write metrics/ztrace recording.
Build/Docs Makefile, src/core/ext/transport/chttp2/GEMINI.md	Adds new sources and updates docs to include GOAWAY.

Chaotic Good Transports (v2 and legacy): Watchers and Telemetry

Layer / File(s)	Summary
Interfaces .../client_transport.{h,cc}, .../server_transport.{h,cc}	Adds StartWatch/StopWatch on client/server; client dispatch holds EventEngine, notifies watcher on disconnect.
Connector .../client/chaotic_good_connector.{h,cc}, .../legacy/client/chaotic_good_connector.{h,cc}	Sets max_concurrent_streams to uint32 max; handshake deadline gating by config.
Endpoints/Telemetry .../data_endpoints.cc, .../legacy/data_endpoints.cc	Enables TCP telemetry only if plugin group exists; sets tracer under that condition.
Server Auth Context .../server/chaotic_good_server.{h,cc}, .../pending_connection.h	Data-connection requests carry handshake args; finish path validates matching auth contexts.

Channelz Expansion and Call Tracing Hooks

Layer / File(s)	Summary
Data Shape src/core/channelz/channelz.h, .../property_list.h, .../channelz_registry.h	Adds new entity types (metrics domain/storage), PropertyList::empty(), and descendants API.
Core Implementation src/core/call/call_spine.{h,cc}, src/core/call/call_filters.h, src/core/call/client_call.{h,cc}	Call becomes a Channelz data source; filters expose ChannelzProperties; client/server calls mark source constructed/destructing and add call-state properties.
Metadata to Properties src/core/call/metadata_channelz.{h,cc}, src/core/call/metadata_batch.{h,cc}	Adds conversion from metadata batches to Channelz property lists and explicit allowlist helper.
Filter Stubs src/core/ext/filters/*/*_filter.h	Adds empty ChannelzProperties() in many filters; compression/stateful_session include richer properties.

Credentials: HTTP Token Fetcher Refactor and Defaults

Layer / File(s)	Summary
Abstraction src/core/credentials/call/token_fetcher/token_fetcher_credentials.{h,cc}	Introduces HttpTokenFetcherCredentials with nested HttpFetchRequest handling HTTP status→absl::Status mapping.
Refactors .../oauth2/oauth2_credentials.{h,cc}, .../gcp_service_account_identity/*	Switches to HttpTokenFetcherCredentials, simplifying fetch flows via lambda callbacks.
Policy Change .../google_default/google_default_credentials.{h,cc}	Removes override that forced DNS SRV queries in Google default channel credentials.
TLS/ALTS Minor .../tls/spiffe_utils.cc	Accepts EC in addition to RSA for kty.

Versioning, Build, Linters, Formatting

Layer / File(s)	Summary
Version Bump Makefile, include/grpcpp/version_info.h	CORE 51→52, C++ 1.76.0→1.78.1; soname updates.
Bazel/Bazelcraft src/core/BUILD, src/compiler/BUILD, .bazelignore	Feature flags, new targets, deps updates; ignore test/bzlmod.
Protobuf Edition Support src/compiler/*	Max edition returns 2024 when protobuf ≥6032000.
Linters/Attrs .pylintrc*, .gitattributes, .clang-format	Ignore generated stubs; linguist updates; include ordering rules.
Headers/Cleanup many #include reorderings	Non-functional include ordering changes for consistency.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor App as App (Credentials)
  participant Cred as HttpTokenFetcherCredentials (Fetcher)
  participant HTTP as HTTP Client
  participant Auth as Auth Server

  App->>Cred: FetchToken(deadline, on_done)
  Cred->>HTTP: StartHttpRequest(deadline, on_complete)
  HTTP-->>Cred: on_complete(StatusOr<grpc_http_response>)
  alt response.ok()
    Cred->>Cred: Parse body, compute expiration
    Cred-->>App: on_done(Token{Bearer <body>, expiry})
  else error
    Cred-->>App: on_done(error)
  end

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sequenceDiagram
  autonumber
  actor CE as Control Endpoint
  participant L as DataConnectionListener
  participant S as Server (Chaotic Good)
  participant DE as Data Endpoint

  CE->>L: RequestDataConnection(handshake_args with auth_ctx)
  note right of L: Store latch + control auth_ctx
  DE->>L: FinishDataConnection(id, endpoint, data auth_ctx)
  alt auth_ctx matches
    L-->>S: Complete data connection
  else mismatch
    L-->>S: Fail with Unauthenticated
  end

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Estimated code review effort

🎯 5 (Critical) | ⏱️ ~120 minutes

Suggested reviewers

• RafaelGSS

Poem

A rabbit with bytes in its burrow so deep,
Buffers and GOAWAYs tucked in a heap.
Flow-control carrots, allocator hay,
Channelz lanterns to light the way.
Tokens hop swiftly on HTTP breeze—
New trails blazed through gRPC trees. 🐇✨

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch santi/upgrade_grpc

[jaz239]

Hey @santigimeno can you please make sure this PR is attached to a ticket? Currently it is not

[RafaelGSS]

RSLGTM

The base branch was changed.

[santigimeno]

Landed in 1023131