add 'empty' function to smart buffer

2 files changed, 16 insertions, 1 deletions

diff --git a/vespalib/src/tests/data/smart_buffer/smart_buffer_test.cpp b/vespalib/src/tests/data/smart_buffer/smart_buffer_test.cpp
index c461da1fcf7..b860aa3326a 100644
--- a/vespalib/src/tests/data/smart_buffer/smart_buffer_test.cpp
+++ b/vespalib/src/tests/data/smart_buffer/smart_buffer_test.cpp
@@ -24,6 +24,7 @@ TEST("require that basic read/write works") {
     SmartBuffer buf(3);
     TEST_DO(checkBuffer("", buf));
     { // read from empty buffer
+        EXPECT_TRUE(buf.empty());
         EXPECT_EQUAL(0u, buf.obtain().size);
     }
     { // write to buffer
@@ -34,6 +35,7 @@ TEST("require that basic read/write works") {
         mem.data[1] = 'b';
         mem.data[2] = 'c';
         EXPECT_EQUAL(&buf, &buf.commit(3));
+        EXPECT_FALSE(buf.empty());
         mem = buf.reserve(0);
         TEST_DO(checkBuffer("abc", buf));
         EXPECT_LESS_EQUAL(0u, mem.size);
@@ -61,6 +63,7 @@ TEST("require that basic read/write works") {
         EXPECT_LESS_EQUAL(5u, mem.size);
     }
     { // read until end
+        EXPECT_FALSE(buf.empty());
         Memory mem = buf.obtain();
         TEST_DO(checkBuffer("cd", buf));
         TEST_DO(checkMemory("cd", mem));
@@ -69,6 +72,7 @@ TEST("require that basic read/write works") {
         TEST_DO(checkBuffer("d", buf));
         TEST_DO(checkMemory("d", mem));
         EXPECT_EQUAL(&buf, &buf.evict(1));
+        EXPECT_TRUE(buf.empty());
         mem = buf.obtain();
         TEST_DO(checkBuffer("", buf));
         TEST_DO(checkMemory("", mem));
@@ -83,16 +87,21 @@ TEST("require that requested initial size is not adjusted") {
 TEST("require that buffer auto-resets when empty") {
     SmartBuffer buf(64);
     EXPECT_EQUAL(buf.reserve(10).size, 64u);
+    EXPECT_TRUE(buf.empty());
     write_buf("abc", buf);
+    EXPECT_FALSE(buf.empty());
     EXPECT_EQUAL(buf.reserve(10).size, 61u);
     buf.evict(3);
+    EXPECT_TRUE(buf.empty());
     EXPECT_EQUAL(buf.reserve(10).size, 64u);
 }
 
 TEST("require that buffer can grow") {
     SmartBuffer buf(64);
     EXPECT_EQUAL(buf.capacity(), 64u);
+    EXPECT_TRUE(buf.empty());
     write_buf("abc", buf);
+    EXPECT_FALSE(buf.empty());
     write_buf("abc", buf);
     buf.evict(3);
     EXPECT_EQUAL(buf.reserve(70).size, size_t(128 - 3));
@@ -103,7 +112,9 @@ TEST("require that buffer can grow") {
 TEST("require that buffer can grow more than 2x") {
     SmartBuffer buf(64);
     EXPECT_EQUAL(buf.capacity(), 64u);
+    EXPECT_TRUE(buf.empty());
     write_buf("abc", buf);
+    EXPECT_FALSE(buf.empty());
     write_buf("abc", buf);
     buf.evict(3);
     EXPECT_EQUAL(buf.reserve(170).size, 170u);
@@ -114,7 +125,9 @@ TEST("require that buffer can grow more than 2x") {
 TEST("require that buffer can be compacted") {
     SmartBuffer buf(16);
     EXPECT_EQUAL(buf.capacity(), 16u);
+    EXPECT_TRUE(buf.empty());
     write_buf("abc", buf);
+    EXPECT_FALSE(buf.empty());
     write_buf("abc", buf);
     buf.evict(3);
     write_buf("abc", buf);
@@ -133,6 +146,7 @@ TEST("require that buffer can be compacted") {
 TEST("require that a completely empty buffer can be created") {
     SmartBuffer buf(0);
     EXPECT_EQUAL(buf.capacity(), 0u);
+    EXPECT_TRUE(buf.empty());
     EXPECT_TRUE(buf.obtain().data == nullptr);
 }
 
diff --git a/vespalib/src/vespa/vespalib/data/smart_buffer.h b/vespalib/src/vespa/vespalib/data/smart_buffer.h
index 17fb7614f0e..fc7042c5eea 100644
--- a/vespalib/src/vespa/vespalib/data/smart_buffer.h
+++ b/vespalib/src/vespa/vespalib/data/smart_buffer.h
@@ -33,9 +33,10 @@ private:
 public:
     SmartBuffer(size_t initial_size);
     ~SmartBuffer();
+    bool empty() const { return (read_len() == 0); }
     size_t capacity() const { return _data.size(); }
     void drop_if_empty() {
-        if ((read_len() == 0) && (_data.size() > 0)) {
+        if (empty() && (_data.size() > 0)) {
             drop();
         }
     }