Move log_namer to log_namer.{cc,h}

logger.{cc,h} is getting too big.  Also move more implementation from
the header to the .cc, and add comments.

Change-Id: Ia342bfade98c71d4d42f769571256c28e2c826d5
diff --git a/aos/events/logging/log_namer.cc b/aos/events/logging/log_namer.cc
new file mode 100644
index 0000000..def0842
--- /dev/null
+++ b/aos/events/logging/log_namer.cc
@@ -0,0 +1,237 @@
+#include "aos/events/logging/log_namer.h"
+
+#include <functional>
+#include <map>
+#include <memory>
+#include <string_view>
+#include <vector>
+
+#include "absl/strings/str_cat.h"
+#include "aos/events/logging/logfile_utils.h"
+#include "aos/events/logging/logger_generated.h"
+#include "aos/events/logging/uuid.h"
+#include "flatbuffers/flatbuffers.h"
+#include "glog/logging.h"
+
+namespace aos {
+namespace logger {
+
+void LogNamer::UpdateHeader(
+    aos::SizePrefixedFlatbufferDetachedBuffer<LogFileHeader> *header,
+    const UUID &uuid, int parts_index) const {
+  header->mutable_message()->mutate_parts_index(parts_index);
+  CHECK_EQ(uuid.string_view().size(),
+           header->mutable_message()->mutable_parts_uuid()->size());
+  std::copy(uuid.string_view().begin(), uuid.string_view().end(),
+            reinterpret_cast<char *>(
+                header->mutable_message()->mutable_parts_uuid()->Data()));
+}
+
+void LocalLogNamer::WriteHeader(
+    aos::SizePrefixedFlatbufferDetachedBuffer<LogFileHeader> *header,
+    const Node *node) {
+  CHECK_EQ(node, this->node());
+  UpdateHeader(header, uuid_, part_number_);
+  data_writer_->WriteSizedFlatbuffer(header->full_span());
+}
+
+DetachedBufferWriter *LocalLogNamer::MakeWriter(const Channel *channel) {
+  CHECK(configuration::ChannelIsSendableOnNode(channel, node()));
+  return data_writer_.get();
+}
+
+void LocalLogNamer::Rotate(
+    const Node *node,
+    aos::SizePrefixedFlatbufferDetachedBuffer<LogFileHeader> *header) {
+  CHECK(node == this->node());
+  ++part_number_;
+  *data_writer_ = std::move(*OpenDataWriter());
+  UpdateHeader(header, uuid_, part_number_);
+  data_writer_->WriteSizedFlatbuffer(header->full_span());
+}
+
+DetachedBufferWriter *LocalLogNamer::MakeTimestampWriter(
+    const Channel *channel) {
+  CHECK(configuration::ChannelIsReadableOnNode(channel, node_))
+      << ": Message is not delivered to this node.";
+  CHECK(node_ != nullptr) << ": Can't log timestamps in a single node world";
+  CHECK(configuration::ConnectionDeliveryTimeIsLoggedOnNode(channel, node_,
+                                                            node_))
+      << ": Delivery times aren't logged for this channel on this node.";
+  return data_writer_.get();
+}
+
+DetachedBufferWriter *LocalLogNamer::MakeForwardedTimestampWriter(
+    const Channel * /*channel*/, const Node * /*node*/) {
+  LOG(FATAL) << "Can't log forwarded timestamps in a singe log file.";
+  return nullptr;
+}
+
+MultiNodeLogNamer::MultiNodeLogNamer(std::string_view base_name,
+                                     const Configuration *configuration,
+                                     const Node *node)
+    : LogNamer(node),
+      base_name_(base_name),
+      configuration_(configuration),
+      uuid_(UUID::Random()),
+      data_writer_(OpenDataWriter()) {}
+
+void MultiNodeLogNamer::WriteHeader(
+    aos::SizePrefixedFlatbufferDetachedBuffer<LogFileHeader> *header,
+    const Node *node) {
+  if (node == this->node()) {
+    UpdateHeader(header, uuid_, part_number_);
+    data_writer_->WriteSizedFlatbuffer(header->full_span());
+  } else {
+    for (std::pair<const Channel *const, DataWriter> &data_writer :
+         data_writers_) {
+      if (node == data_writer.second.node) {
+        UpdateHeader(header, data_writer.second.uuid,
+                     data_writer.second.part_number);
+        data_writer.second.writer->WriteSizedFlatbuffer(header->full_span());
+      }
+    }
+  }
+}
+
+void MultiNodeLogNamer::Rotate(
+    const Node *node,
+    aos::SizePrefixedFlatbufferDetachedBuffer<LogFileHeader> *header) {
+  if (node == this->node()) {
+    ++part_number_;
+    *data_writer_ = std::move(*OpenDataWriter());
+    UpdateHeader(header, uuid_, part_number_);
+    data_writer_->WriteSizedFlatbuffer(header->full_span());
+  } else {
+    for (std::pair<const Channel *const, DataWriter> &data_writer :
+         data_writers_) {
+      if (node == data_writer.second.node) {
+        ++data_writer.second.part_number;
+        data_writer.second.rotate(data_writer.first, &data_writer.second);
+        UpdateHeader(header, data_writer.second.uuid,
+                     data_writer.second.part_number);
+        data_writer.second.writer->WriteSizedFlatbuffer(header->full_span());
+      }
+    }
+  }
+}
+
+DetachedBufferWriter *MultiNodeLogNamer::MakeWriter(const Channel *channel) {
+  // See if we can read the data on this node at all.
+  const bool is_readable =
+      configuration::ChannelIsReadableOnNode(channel, this->node());
+  if (!is_readable) {
+    return nullptr;
+  }
+
+  // Then, see if we are supposed to log the data here.
+  const bool log_message =
+      configuration::ChannelMessageIsLoggedOnNode(channel, this->node());
+
+  if (!log_message) {
+    return nullptr;
+  }
+
+  // Now, sort out if this is data generated on this node, or not.  It is
+  // generated if it is sendable on this node.
+  if (configuration::ChannelIsSendableOnNode(channel, this->node())) {
+    return data_writer_.get();
+  }
+
+  // Ok, we have data that is being forwarded to us that we are supposed to
+  // log.  It needs to be logged with send timestamps, but be sorted enough
+  // to be able to be processed.
+  CHECK(data_writers_.find(channel) == data_writers_.end());
+
+  // Track that this node is being logged.
+  const Node *source_node = configuration::GetNode(
+      configuration_, channel->source_node()->string_view());
+
+  if (std::find(nodes_.begin(), nodes_.end(), source_node) == nodes_.end()) {
+    nodes_.emplace_back(source_node);
+  }
+
+  DataWriter data_writer;
+  data_writer.node = source_node;
+  data_writer.rotate = [this](const Channel *channel, DataWriter *data_writer) {
+    OpenWriter(channel, data_writer);
+  };
+  data_writer.rotate(channel, &data_writer);
+
+  return data_writers_.insert(std::make_pair(channel, std::move(data_writer)))
+      .first->second.writer.get();
+}
+
+DetachedBufferWriter *MultiNodeLogNamer::MakeForwardedTimestampWriter(
+    const Channel *channel, const Node *node) {
+  // See if we can read the data on this node at all.
+  const bool is_readable =
+      configuration::ChannelIsReadableOnNode(channel, this->node());
+  CHECK(is_readable) << ": " << configuration::CleanedChannelToString(channel);
+
+  CHECK(data_writers_.find(channel) == data_writers_.end());
+
+  if (std::find(nodes_.begin(), nodes_.end(), node) == nodes_.end()) {
+    nodes_.emplace_back(node);
+  }
+
+  DataWriter data_writer;
+  data_writer.node = node;
+  data_writer.rotate = [this](const Channel *channel, DataWriter *data_writer) {
+    OpenForwardedTimestampWriter(channel, data_writer);
+  };
+  data_writer.rotate(channel, &data_writer);
+
+  return data_writers_.insert(std::make_pair(channel, std::move(data_writer)))
+      .first->second.writer.get();
+}
+
+DetachedBufferWriter *MultiNodeLogNamer::MakeTimestampWriter(
+    const Channel *channel) {
+  const bool log_delivery_times =
+      (this->node() == nullptr)
+          ? false
+          : configuration::ConnectionDeliveryTimeIsLoggedOnNode(
+                channel, this->node(), this->node());
+  if (!log_delivery_times) {
+    return nullptr;
+  }
+
+  return data_writer_.get();
+}
+
+void MultiNodeLogNamer::OpenForwardedTimestampWriter(const Channel *channel,
+                                                     DataWriter *data_writer) {
+  std::string filename =
+      absl::StrCat(base_name_, "_timestamps", channel->name()->string_view(),
+                   "/", channel->type()->string_view(), ".part",
+                   data_writer->part_number, ".bfbs");
+
+  if (!data_writer->writer) {
+    data_writer->writer = std::make_unique<DetachedBufferWriter>(filename);
+  } else {
+    *data_writer->writer = DetachedBufferWriter(filename);
+  }
+}
+
+void MultiNodeLogNamer::OpenWriter(const Channel *channel,
+                                   DataWriter *data_writer) {
+  const std::string filename = absl::StrCat(
+      base_name_, "_", channel->source_node()->string_view(), "_data",
+      channel->name()->string_view(), "/", channel->type()->string_view(),
+      ".part", data_writer->part_number, ".bfbs");
+  if (!data_writer->writer) {
+    data_writer->writer = std::make_unique<DetachedBufferWriter>(filename);
+  } else {
+    *data_writer->writer = DetachedBufferWriter(filename);
+  }
+}
+
+std::unique_ptr<DetachedBufferWriter> MultiNodeLogNamer::OpenDataWriter() {
+  return std::make_unique<DetachedBufferWriter>(
+      absl::StrCat(base_name_, "_", node()->name()->string_view(), "_data.part",
+                   part_number_, ".bfbs"));
+}
+
+}  // namespace logger
+}  // namespace aos