commit 354697ac6dd776b1b5407b48a74b6f740d4832e9
author Brian Silverman <bsilver16384@gmail.com> Tue Sep 22 21:06:32 2020 -0700
committer Brian Silverman <bsilver16384@gmail.com> Thu Sep 24 16:55:51 2020 -0700
tree 34d1a33b270da1d1b98c4ba1a571b0be8094fe2a
parent f51499a64327d52d93d6452f2003660f420003b5

Use ResizeableBuffer for FlatbufferVector

This speeds up fastbuild log reading a lot.

Change-Id: I4452096a9a1d5b0330cbfeed5762dcc4f15d0d20

aos/events/logging/logfile_utils.cc

diff --git a/aos/events/logging/logfile_utils.cc b/aos/events/logging/logfile_utils.cc
index c7f013d..9d8145d 100644
--- a/aos/events/logging/logfile_utils.cc
+++ b/aos/events/logging/logfile_utils.cc
@@ -300,8 +300,10 @@
       << ": Failed to read header from: " << filename;
 
   // And copy the config so we have it forever, removing the size prefix.
-  std::vector<uint8_t> data(
-      config_data.begin() + sizeof(flatbuffers::uoffset_t), config_data.end());
+  ResizeableBuffer data;
+  data.resize(config_data.size() - sizeof(flatbuffers::uoffset_t));
+  memcpy(data.data(), config_data.begin() + sizeof(flatbuffers::uoffset_t),
+         data.size());
   return FlatbufferVector<LogFileHeader>(std::move(data));
 }
 
@@ -317,9 +319,11 @@
         << ": Failed to read data from: " << filename;
   }
 
-  // And copy the data so we have it forever.
-  std::vector<uint8_t> data(data_span.begin() + sizeof(flatbuffers::uoffset_t),
-                            data_span.end());
+  // And copy the config so we have it forever, removing the size prefix.
+  ResizeableBuffer data;
+  data.resize(data_span.size() - sizeof(flatbuffers::uoffset_t));
+  memcpy(data.data(), data_span.begin() + sizeof(flatbuffers::uoffset_t),
+         data.size());
   return FlatbufferVector<MessageHeader>(std::move(data));
 }
 
@@ -334,8 +338,11 @@
       << ": Failed to read header from: " << filename;
 
   // And copy the header data so we have it forever.
-  std::vector<uint8_t> header_data_copy(
-      header_data.begin() + sizeof(flatbuffers::uoffset_t), header_data.end());
+  ResizeableBuffer header_data_copy;
+  header_data_copy.resize(header_data.size() - sizeof(flatbuffers::uoffset_t));
+  memcpy(header_data_copy.data(),
+         header_data.begin() + sizeof(flatbuffers::uoffset_t),
+         header_data_copy.size());
   raw_log_file_header_ =
       FlatbufferVector<LogFileHeader>(std::move(header_data_copy));
 
@@ -352,8 +359,12 @@
     return std::nullopt;
   }
 
-  FlatbufferVector<MessageHeader> result{std::vector<uint8_t>(
-      msg_data.begin() + sizeof(flatbuffers::uoffset_t), msg_data.end())};
+  ResizeableBuffer result_buffer;
+  result_buffer.resize(msg_data.size() - sizeof(flatbuffers::uoffset_t));
+  memcpy(result_buffer.data(),
+         msg_data.begin() + sizeof(flatbuffers::uoffset_t),
+         result_buffer.size());
+  FlatbufferVector<MessageHeader> result(std::move(result_buffer));
 
   const monotonic_clock::time_point timestamp = monotonic_clock::time_point(
       chrono::nanoseconds(result.message().monotonic_sent_time()));