Merge "logd: remove min heap in SerializedFlushToState"

#include "SerializedFlushToState.h"

#include <limits>

#include <android-base/logging.h>

SerializedFlushToState::SerializedFlushToState(uint64_t start, LogMask log_mask)

    log_positions_[log_id].emplace(log_position);

}

void SerializedFlushToState::AddMinHeapEntry(log_id_t log_id) {

void SerializedFlushToState::UpdateLogsNeeded(log_id_t log_id) {

    auto& buffer_it = log_positions_[log_id]->buffer_it;

    auto read_offset = log_positions_[log_id]->read_offset;

    // If there is another log to read in this buffer, add it to the min heap.

    // If there is another log to read in this buffer, let it be read.

    if (read_offset < buffer_it->write_offset()) {

        auto* entry = buffer_it->log_entry(read_offset);

        min_heap_.emplace(log_id, entry);

        logs_needed_from_next_position_[log_id] = false;

    } else if (read_offset == buffer_it->write_offset()) {

        // If there are no more logs to read in this buffer and it's the last buffer, then

        // set logs_needed_from_next_position_ to wait until more logs get logged.

            if (buffer_it->write_offset() == 0) {

                logs_needed_from_next_position_[log_id] = true;

            } else {

                auto* entry = buffer_it->log_entry(0);

                min_heap_.emplace(log_id, entry);

                logs_needed_from_next_position_[log_id] = false;

            }

        }

    } else {

            }

            CreateLogPosition(i);

        }

        logs_needed_from_next_position_[i] = false;

        // If it wasn't possible to insert, logs_needed_from_next_position will be set back to true.

        AddMinHeapEntry(i);

        UpdateLogsNeeded(i);

    }

}

MinHeapElement SerializedFlushToState::PopNextUnreadLog() {

    auto top = min_heap_.top();

    min_heap_.pop();

bool SerializedFlushToState::HasUnreadLogs() {

    CheckForNewLogs();

    log_id_for_each(i) {

        if (log_positions_[i] && !logs_needed_from_next_position_[i]) {

            return true;

        }

    }

    return false;

}

    auto* entry = top.entry;

    auto log_id = top.log_id;

LogWithId SerializedFlushToState::PopNextUnreadLog() {

    uint64_t min_sequence = std::numeric_limits<uint64_t>::max();

    log_id_t log_id;

    const SerializedLogEntry* entry = nullptr;

    log_id_for_each(i) {

        if (!log_positions_[i] || logs_needed_from_next_position_[i]) {

            continue;

        }

        if (log_positions_[i]->log_entry()->sequence() < min_sequence) {

            log_id = i;

            entry = log_positions_[i]->log_entry();

            min_sequence = entry->sequence();

        }

    }

    CHECK_NE(nullptr, entry);

    log_positions_[log_id]->read_offset += entry->total_len();

    logs_needed_from_next_position_[log_id] = true;

    return top;

    return {log_id, entry};

}

void SerializedFlushToState::Prune(log_id_t log_id,

        return;

    }

    // // Decrease the ref count since we're deleting our reference.

    // Decrease the ref count since we're deleting our reference.

    buffer_it->DecReaderRefCount();

    // Delete in the reference.

    log_positions_[log_id].reset();

    // Remove the MinHeapElement referencing log_id, if it exists, but retain the others.

    std::vector<MinHeapElement> old_elements;

    while (!min_heap_.empty()) {

        auto& element = min_heap_.top();

        if (element.log_id != log_id) {

            old_elements.emplace_back(element);

        }

        min_heap_.pop();

    }

    for (auto&& element : old_elements) {

        min_heap_.emplace(element);

    }

    // Finally set logs_needed_from_next_position_, so CheckForNewLogs() will re-create the

    // log_position_ object during the next read.

    logs_needed_from_next_position_[log_id] = true;

struct LogPosition {

    std::list<SerializedLogChunk>::iterator buffer_it;

    int read_offset;

    const SerializedLogEntry* log_entry() const { return buffer_it->log_entry(read_offset); }

};

struct MinHeapElement {

    MinHeapElement(log_id_t log_id, const SerializedLogEntry* entry)

        : log_id(log_id), entry(entry) {}

struct LogWithId {

    log_id_t log_id;

    const SerializedLogEntry* entry;

    // The change of comparison operators is intentional, std::priority_queue uses operator<() to

    // compare but creates a max heap.  Since we want a min heap, we return the opposite result.

    bool operator<(const MinHeapElement& rhs) const {

        return entry->sequence() > rhs.entry->sequence();

    }

};

// This class tracks the specific point where a FlushTo client has read through the logs.  It

// directly references the std::list<> iterators from the parent SerializedLogBuffer and the offset

// into each log chunk where it has last read.  All interactions with this class, except for its

// construction, must be done with SerializedLogBuffer::lock_ held.  No log chunks that it

// references may be pruned, which is handled by ensuring prune does not touch any log chunk with

// highest sequence number greater or equal to start().

// construction, must be done with SerializedLogBuffer::lock_ held.

class SerializedFlushToState : public FlushToState {

  public:

    // Initializes this state object.  For each log buffer set in log_mask, this sets

        if (logs_ == nullptr) logs_ = logs;

    }

    bool HasUnreadLogs() {

        CheckForNewLogs();

        return !min_heap_.empty();

    }

    // Updates the state of log_positions_ and logs_needed_from_next_position_ then returns true if

    // there are any unread logs, false otherwise.

    bool HasUnreadLogs();

    // Pops the next unread log from the min heap and sets logs_needed_from_next_position_ to

    // indicate that we're waiting for more logs from the associated log buffer.

    MinHeapElement PopNextUnreadLog();

    // Returns the next unread log and sets logs_needed_from_next_position_ to indicate that we're

    // waiting for more logs from the associated log buffer.

    LogWithId PopNextUnreadLog();

    // If the parent log buffer prunes logs, the reference that this class contains may become

    // invalid, so this must be called first to drop the reference to buffer_it, if any.

    void Prune(log_id_t log_id, const std::list<SerializedLogChunk>::iterator& buffer_it);

  private:

    // If there is a log in the serialized log buffer for `log_id` at the read_offset, add it to the

    // min heap for reading, otherwise set logs_needed_from_next_position_ to indicate that we're

    // waiting for the next log.

    void AddMinHeapEntry(log_id_t log_id);

    // Set logs_needed_from_next_position_[i] to indicate if log_positions_[i] points to an unread

    // log or to the point at which the next log will appear.

    void UpdateLogsNeeded(log_id_t log_id);

    // Create a LogPosition object for the given log_id by searching through the log chunks for the

    // first chunk and then first log entry within that chunk that is greater or equal to start().

    void CreateLogPosition(log_id_t log_id);

    // Checks to see if any log buffers set in logs_needed_from_next_position_ have new logs and

    // calls AddMinHeapEntry() if so.

    // calls UpdateLogsNeeded() if so.

    void CheckForNewLogs();

    std::list<SerializedLogChunk>* logs_ = nullptr;

    // next_log_position == logs_write_position_)`.  These will be re-checked in each

    // loop in case new logs came in.

    std::bitset<LOG_ID_MAX> logs_needed_from_next_position_ = {};

    // A min heap that has up to one entry per log buffer, sorted by sequence number, of the next

    // element that this reader should read.

    std::priority_queue<MinHeapElement> min_heap_;

};

    EXPECT_FALSE(state.HasUnreadLogs());

}

TEST(SerializedFlushToState, Prune) {

    auto chunk = SerializedLogChunk{kChunkSize};

    chunk.Log(1, log_time(), 0, 1, 1, "abc", 3);

    chunk.Log(2, log_time(), 0, 1, 1, "abc", 3);

    chunk.Log(3, log_time(), 0, 1, 1, "abc", 3);

    chunk.FinishWriting();

    std::list<SerializedLogChunk> log_chunks[LOG_ID_MAX];

    log_chunks[LOG_ID_MAIN].emplace_back(std::move(chunk));

    auto state = SerializedFlushToState{1, kLogMaskAll};

    state.InitializeLogs(log_chunks);

    ASSERT_TRUE(state.HasUnreadLogs());

    state.Prune(LOG_ID_MAIN, log_chunks[LOG_ID_MAIN].begin());

}

    state.InitializeLogs(logs_);

    while (state.HasUnreadLogs()) {

        MinHeapElement top = state.PopNextUnreadLog();

        LogWithId top = state.PopNextUnreadLog();

        auto* entry = top.entry;

        auto log_id = top.log_id;

#include <sys/types.h>

#include <android-base/logging.h>

#include "LogWriter.h"

#include "SerializedData.h"

#include "SerializedLogEntry.h"

    }

    const SerializedLogEntry* log_entry(int offset) const {

        CHECK(writer_active_ || reader_ref_count_ > 0);

        return reinterpret_cast<const SerializedLogEntry*>(data() + offset);

    }

    const uint8_t* data() const { return contents_.data(); }