Simpleperf: Add SPLIT and SPLIT_END records to handle big records.

Previously we split KernelSymbolRecord because it is > 65535. Then
I found TracingDataRecord can also be > 65535. So it is better to
handle big records when reading and writing perf.data.
record_file_writer.cpp splits a big record into multiple SPLIT
records followed by a SPLIT_END record, and record_file_reader.cpp
restores the big record when reading SPLIT and SPLIT_END records.
Also Add RecordHeader to represent record having size > 65535.

Bug: 29581559
Change-Id: I0b4556988f77b3431c7f1a28fce65cf225d6a067
Test: run simpleperf_unit_test.

1 files changed, 1 insertions, 6 deletions

diff --git a/simpleperf/thread_tree.cpp b/simpleperf/thread_tree.cpp
index 58b02006..8e4e9e9d 100644
--- a/simpleperf/thread_tree.cpp
+++ b/simpleperf/thread_tree.cpp
@@ -253,12 +253,7 @@ void ThreadTree::Update(const Record& record) {
     ForkThread(r.data.pid, r.data.tid, r.data.ppid, r.data.ptid);
   } else if (record.type() == SIMPLE_PERF_RECORD_KERNEL_SYMBOL) {
     const auto& r = *static_cast<const KernelSymbolRecord*>(&record);
-    static std::string kallsyms;
-    kallsyms += r.kallsyms;
-    if (r.end_of_symbols) {
-      Dso::SetKallsyms(std::move(kallsyms));
-      kallsyms.clear();
-    }
+    Dso::SetKallsyms(std::move(r.kallsyms));
   } else if (record.type() == SIMPLE_PERF_RECORD_DSO) {
     auto& r = *static_cast<const DsoRecord*>(&record);
     Dso* dso = nullptr;