| // Copyright 2021 The Pigweed Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| // use this file except in compliance with the License. You may obtain a copy of |
| // the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| // License for the specific language governing permissions and limitations under |
| // the License. |
| #include "pw_multisink/multisink.h" |
| |
| #include <cstring> |
| |
| #include "pw_assert/check.h" |
| #include "pw_status/try.h" |
| #include "pw_varint/varint.h" |
| |
| namespace pw { |
| namespace multisink { |
| |
| void MultiSink::HandleEntry(ConstByteSpan entry) { |
| std::lock_guard lock(lock_); |
| PW_DCHECK_OK(ring_buffer_.PushBack(entry, sequence_id_++)); |
| NotifyListeners(); |
| } |
| |
| void MultiSink::HandleDropped(uint32_t drop_count) { |
| std::lock_guard lock(lock_); |
| sequence_id_ += drop_count; |
| NotifyListeners(); |
| } |
| |
| Result<ConstByteSpan> MultiSink::GetEntry(Drain& drain, |
| ByteSpan buffer, |
| uint32_t& drop_count_out) { |
| size_t bytes_read = 0; |
| uint32_t entry_sequence_id = 0; |
| drop_count_out = 0; |
| |
| std::lock_guard lock(lock_); |
| PW_DCHECK_PTR_EQ(drain.multisink_, this); |
| |
| const Status peek_status = drain.reader_.PeekFrontWithPreamble( |
| buffer, entry_sequence_id, bytes_read); |
| if (peek_status.IsOutOfRange()) { |
| // If the drain has caught up, report the last handled sequence ID so that |
| // it can still process any dropped entries. |
| entry_sequence_id = sequence_id_ - 1; |
| } else if (!peek_status.ok()) { |
| // Exit immediately if the result isn't OK or OUT_OF_RANGE, as the |
| // entry_entry_sequence_id cannot be used for computation. Later invocations |
| // to GetEntry will permit readers to determine how far the sequence ID |
| // moved forward. |
| return peek_status; |
| } |
| |
| // Compute the drop count delta by comparing this entry's sequence ID with the |
| // last sequence ID this drain successfully read. |
| // |
| // The drop count calculation simply computes the difference between the |
| // current and last sequence IDs. Consecutive successful reads will always |
| // differ by one at least, so it is subtracted out. If the read was not |
| // successful, the difference is not adjusted. |
| drop_count_out = entry_sequence_id - drain.last_handled_sequence_id_ - |
| (peek_status.ok() ? 1 : 0); |
| drain.last_handled_sequence_id_ = entry_sequence_id; |
| |
| // The Peek above may have failed due to OutOfRange, now that we've set the |
| // drop count see if we should return before attempting to pop. |
| if (peek_status.IsOutOfRange()) { |
| return peek_status; |
| } |
| |
| // Success, pop the oldest entry! |
| PW_CHECK(drain.reader_.PopFront().ok()); |
| return std::as_bytes(buffer.first(bytes_read)); |
| } |
| |
| void MultiSink::AttachDrain(Drain& drain) { |
| std::lock_guard lock(lock_); |
| PW_DCHECK_PTR_EQ(drain.multisink_, nullptr); |
| drain.multisink_ = this; |
| drain.last_handled_sequence_id_ = sequence_id_ - 1; |
| PW_CHECK_OK(ring_buffer_.AttachReader(drain.reader_)); |
| } |
| |
| void MultiSink::DetachDrain(Drain& drain) { |
| std::lock_guard lock(lock_); |
| PW_DCHECK_PTR_EQ(drain.multisink_, this); |
| drain.multisink_ = nullptr; |
| PW_CHECK_OK(ring_buffer_.DetachReader(drain.reader_), |
| "The drain wasn't already attached."); |
| } |
| |
| void MultiSink::AttachListener(Listener& listener) { |
| std::lock_guard lock(lock_); |
| listeners_.push_back(listener); |
| } |
| |
| void MultiSink::DetachListener(Listener& listener) { |
| std::lock_guard lock(lock_); |
| [[maybe_unused]] bool was_detached = listeners_.remove(listener); |
| PW_DCHECK(was_detached, "The listener was already attached."); |
| } |
| |
| void MultiSink::Clear() { |
| std::lock_guard lock(lock_); |
| ring_buffer_.Clear(); |
| } |
| |
| void MultiSink::NotifyListeners() { |
| for (auto& listener : listeners_) { |
| listener.OnNewEntryAvailable(); |
| } |
| } |
| |
| Result<ConstByteSpan> MultiSink::Drain::GetEntry(ByteSpan buffer, |
| uint32_t& drop_count_out) { |
| PW_DCHECK_NOTNULL(multisink_); |
| return multisink_->GetEntry(*this, buffer, drop_count_out); |
| } |
| |
| } // namespace multisink |
| } // namespace pw |