[XRay] FDR Record Producer/Consumer Implementation

Summary:
This patch defines two new base types called `RecordProducer` and
`RecordConsumer` which have default implementations for convenience
(particularly for testing).

A `RecordProducer` implementation has one member function called
`produce()` which serves as a factory constructor for `Record`
instances. This code exercises the `RecordInitializer` code path in the
implementation for `FileBasedRecordProducer`.

A `RecordConsumer` has a single member function called `consume(...)`
which, as the name implies, consumes instances of
`std::unique_ptr<Record>`. We have two implementations, one of which is
used in the test to generate a vector of `std::unique_ptr<Record>`
similar to how the `LogBuilder` implementation works.

We introduce a test in `FDRProducerConsumerTest` which ensures that
records we write through the `FDRTraceWriter` can be loaded by the
`FileBasedRecordProducer`. The record(s) loaded this way are written
again through the `FDRTraceWriter` into a separate string, which we then
compare. This ensures that the read-in bytes to create the `Record`
instances in memory can be replicated when written out through the
`FDRTraceWriter`.

This change depends on D51210 and is part of the refactoring of D50441
into smaller, more focused changes.

Reviewers: eizan, kpw

Subscribers: mgorny, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D51289

llvm-svn: 341180

1 files changed, 38 insertions, 0 deletions

diff --git a/llvm/lib/XRay/LogBuilderConsumer.cpp b/llvm/lib/XRay/LogBuilderConsumer.cpp
new file mode 100644
index 00000000000..88b7d2d728b
--- /dev/null
+++ b/llvm/lib/XRay/LogBuilderConsumer.cpp
@@ -0,0 +1,38 @@
+//===- FDRRecordConsumer.h - XRay Flight Data Recorder Mode Records -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/XRay/FDRRecordConsumer.h"
+
+namespace llvm {
+namespace xray {
+
+Error LogBuilderConsumer::consume(std::unique_ptr<Record> R) {
+  if (!R)
+    return createStringError(
+        std::make_error_code(std::errc::invalid_argument),
+        "Must not call RecordConsumer::consume() with a null pointer.");
+  Records.push_back(std::move(R));
+  return Error::success();
+}
+
+Error PipelineConsumer::consume(std::unique_ptr<Record> R) {
+  if (!R)
+    return createStringError(
+        std::make_error_code(std::errc::invalid_argument),
+        "Must not call RecordConsumer::consume() with a null pointer.");
+
+  // We apply all of the visitors in order, and concatenate errors
+  // appropriately.
+  Error Result = Error::success();
+  for (auto *V : Visitors)
+    Result = joinErrors(std::move(Result), R->apply(*V));
+  return Result;
+}
+
+} // namespace xray
+} // namespace llvm