commit 62bb7a093fed1b75e398d333fe599a3568955e27
author Hridya Valsaraju <hridya@google.com> Fri Sep 23 10:44:04 2016 -0700
committer Hridya Valsaraju <hridya@google.com> Fri Sep 23 15:40:12 2016 -0700
tree 3f4fc724fa1673808b42c0a34355ac40104889b9
parent 4fe70f0d17c3f228af95c452d95037b44e0aa28b

Add another constructor to MQDescriptor.

The new constructor for MQDescriptor will create
a default GrantorDescriptor with fdIndex for all
grantors set to 0 and contiguous offsets.

Bug: 31710802
Test: Built and run all existing FMQ unit tests
and benchmarks.

Change-Id: Ic4ad707917bf37be2a44c65c1b101ee2bd1e2290

MQDescriptor.cpp

diff --git a/MQDescriptor.cpp b/MQDescriptor.cpp
index e768589..d620512 100644
--- a/MQDescriptor.cpp
+++ b/MQDescriptor.cpp
@@ -39,6 +39,32 @@
     }
 }
 
+MQDescriptor::MQDescriptor(size_t bufferSize, native_handle_t *nHandle,
+                           int32_t flags, size_t messageSize)
+    : mHandle(nHandle), mQuantum(messageSize), mFlags(flags) {
+    mGrantors.resize(kMinGrantorCount);
+    /*
+     * Create a default grantor descriptor for read, write pointers and
+     * the data buffer. fdIndex parameter is set to 0 by default and
+     * the offset for each grantor is contiguous.
+     */
+    mGrantors[READPTRPOS] = {
+        0 /* grantor flags */, 0 /* fdIndex */, 0 /* offset */,
+        sizeof(RingBufferPosition) /* extent */
+    };
+
+    mGrantors[WRITEPTRPOS] = {
+        0 /* grantor flags */,
+        0 /* fdIndex */,
+        sizeof(RingBufferPosition) /* offset */,
+        sizeof(RingBufferPosition) /* extent */
+    };
+    mGrantors[DATAPTRPOS] = {
+        0 /* grantor flags */, 0 /* fdIndex */,
+        2 * sizeof(RingBufferPosition) /* offset */, bufferSize /* extent */
+    };
+}
+
 MQDescriptor::MQDescriptor(const MQDescriptor &other)
     : mGrantors(other.mGrantors),
       mHandle(nullptr),

include/hidl/MQDescriptor.h

diff --git a/include/hidl/MQDescriptor.h b/include/hidl/MQDescriptor.h
index 327b61c..c01a902 100644
--- a/include/hidl/MQDescriptor.h
+++ b/include/hidl/MQDescriptor.h
@@ -25,19 +25,22 @@
 namespace android {
 namespace hardware {
 
+typedef uint64_t RingBufferPosition;
+
 struct GrantorDescriptor {
     uint32_t flags;
     uint32_t fdIndex;
     uint32_t offset;
-    uint32_t extent;
+    size_t extent;
 };
 
-enum GrantorType : int { READPTRPOS = 0, WRITEPTRPOS, DATAPTRPOS };
-
 struct MQDescriptor {
     MQDescriptor(
             const std::vector<GrantorDescriptor>& grantors,
-            native_handle_t* nhandle, int32_t flags, size_t size);
+            native_handle_t* nHandle, int32_t flags, size_t size);
+
+    MQDescriptor(size_t bufferSize, native_handle_t* nHandle, int32_t flags,
+                 size_t messageSize);
 
     ~MQDescriptor();
 
@@ -64,6 +67,12 @@
     size_t countGrantors() const { return mGrantors.size(); }
     std::vector<GrantorDescriptor> getGrantors() const;
     const sp<NativeHandle> getNativeHandle() const;
+    /*
+     * There should atleast be GrantorDescriptors for the read counter, write
+     * counter and data buffer.
+     */
+    static constexpr int32_t kMinGrantorCount = 3;
+    enum GrantorType : int { READPTRPOS = 0, WRITEPTRPOS, DATAPTRPOS };
 
 private:
     ::android::hardware::hidl_vec<GrantorDescriptor> mGrantors;