Add clear method to ProtoOutputStream so it is reusable by just

rewinding its internal pointer.

Bug: 72319159
Test: atest incidentd_test and atest statsd_test
Change-Id: Id046b987a7460d68300e5d4d46ae56aec1eba2d0

4 files changed, 29 insertions, 0 deletions

diff --git a/libs/protoutil/include/android/util/EncodedBuffer.h b/libs/protoutil/include/android/util/EncodedBuffer.h
index e568e4cf02fc..0a8a5aa347ba 100644
--- a/libs/protoutil/include/android/util/EncodedBuffer.h
+++ b/libs/protoutil/include/android/util/EncodedBuffer.h
@@ -64,6 +64,11 @@ public:
         size_t mOffset;
     };
 
+    /**
+     * Clears the buffer by rewinding its write pointer to avoid de/allocate buffers in heap.
+     */
+    void clear();
+
     /******************************** Write APIs ************************************************/
 
     /**
diff --git a/libs/protoutil/include/android/util/ProtoOutputStream.h b/libs/protoutil/include/android/util/ProtoOutputStream.h
index faea9b21311d..52830d397772 100644
--- a/libs/protoutil/include/android/util/ProtoOutputStream.h
+++ b/libs/protoutil/include/android/util/ProtoOutputStream.h
@@ -123,6 +123,11 @@ public:
     EncodedBuffer::iterator data(); // Get the reader apis of the data.
     bool flush(int fd); // Flush data directly to a file descriptor.
 
+    /**
+     * Clears the ProtoOutputStream so the buffer can be reused instead of deallocation/allocation again.
+     */
+    void clear();
+
     // Please don't use the following functions to dump protos unless you are familiar with protobuf encoding.
     void writeRawVarint(uint64_t varint);
     void writeLengthDelimitedHeader(uint32_t id, size_t size);
diff --git a/libs/protoutil/src/EncodedBuffer.cpp b/libs/protoutil/src/EncodedBuffer.cpp
index 435ae8836217..3a5e2e9ef5d0 100644
--- a/libs/protoutil/src/EncodedBuffer.cpp
+++ b/libs/protoutil/src/EncodedBuffer.cpp
@@ -106,6 +106,13 @@ EncodedBuffer::at(const Pointer& p) const
     return mBuffers[p.index()] + p.offset();
 }
 
+void
+EncodedBuffer::clear()
+{
+    mWp.rewind();
+    mEp.rewind();
+}
+
 /******************************** Write APIs ************************************************/
 size_t
 EncodedBuffer::size() const
diff --git a/libs/protoutil/src/ProtoOutputStream.cpp b/libs/protoutil/src/ProtoOutputStream.cpp
index f24abaed2dce..9d9ffec4c588 100644
--- a/libs/protoutil/src/ProtoOutputStream.cpp
+++ b/libs/protoutil/src/ProtoOutputStream.cpp
@@ -36,6 +36,18 @@ ProtoOutputStream::~ProtoOutputStream()
 {
 }
 
+
+void
+ProtoOutputStream::clear()
+{
+    mBuffer.clear();
+    mCopyBegin = 0;
+    mCompact = false;
+    mDepth = 0;
+    mObjectId = 0;
+    mExpectedObjectToken = 0LL;
+}
+
 bool
 ProtoOutputStream::write(uint64_t fieldId, double val)
 {