let obtain set eof flag and read set failed state

3 files changed, 52 insertions, 12 deletions

diff --git a/vespalib/src/tests/data/input_reader/input_reader_test.cpp b/vespalib/src/tests/data/input_reader/input_reader_test.cpp
index 345baf12293..31b440f9800 100644
--- a/vespalib/src/tests/data/input_reader/input_reader_test.cpp
+++ b/vespalib/src/tests/data/input_reader/input_reader_test.cpp
@@ -48,8 +48,9 @@ TEST("input reader smoke test") {
         EXPECT_TRUE(!src.failed());
         EXPECT_EQUAL(src.get_offset(), strlen(data));
         EXPECT_EQUAL(src.obtain(), 0u);
-        EXPECT_TRUE(src.failed());
+        EXPECT_TRUE(!src.failed());
         EXPECT_EQUAL(src.read(5), Memory());
+        EXPECT_TRUE(src.failed());
         EXPECT_EQUAL(src.read(), '\0');
         EXPECT_EQUAL(src.obtain(), 0u);
         EXPECT_EQUAL(src.get_offset(), strlen(data));
@@ -100,4 +101,29 @@ TEST("require that reading a byte sequence crossing the end of input fails") {
     }
 }
 
+TEST("expect that obtain sets eof but not failure state on input reader") {
+    const char *data = "12345";
+    for (bool byte_first: {true, false}) {
+        MemoryInput input(data);
+        InputReader src(input);
+        EXPECT_EQUAL(src.obtain(), 5);
+        EXPECT_EQUAL(src.read(5), Memory("12345"));
+        EXPECT_TRUE(!src.failed());
+        EXPECT_TRUE(!src.eof());
+        EXPECT_EQUAL(src.obtain(), 0);
+        EXPECT_TRUE(src.eof());
+        EXPECT_TRUE(!src.failed());
+        if (byte_first) {
+            EXPECT_EQUAL(src.read(), 0);
+            EXPECT_EQUAL(src.read(5), Memory());
+        } else {
+            EXPECT_EQUAL(src.read(5), Memory());
+            EXPECT_EQUAL(src.read(), 0);
+        }
+        EXPECT_TRUE(src.failed());
+        EXPECT_EQUAL(src.get_error_message(), vespalib::string("input underflow"));
+        EXPECT_EQUAL(src.obtain(), 0);
+    }
+}
+
 TEST_MAIN() { TEST_RUN_ALL(); }
diff --git a/vespalib/src/vespa/vespalib/data/input_reader.cpp b/vespalib/src/vespa/vespalib/data/input_reader.cpp
index 031cb9b1624..b71935c795b 100644
--- a/vespalib/src/vespa/vespalib/data/input_reader.cpp
+++ b/vespalib/src/vespa/vespalib/data/input_reader.cpp
@@ -9,17 +9,24 @@ namespace vespalib {
 size_t
 InputReader::obtain_slow()
 {
-    if (!failed()) {
-        _data = _input.evict(_pos).obtain();
-        _bytes_evicted += _pos;
-        _pos = 0;
-        if (_data.size == 0) {
-            fail("input underflow");
-        }
+    _data = _input.evict(_pos).obtain();
+    _bytes_evicted += _pos;
+    _pos = 0;
+    if (_data.size == 0) {
+        _eof = true;
     }
     return size();
 }
 
+char
+InputReader::read_slow()
+{
+    if (!failed()) {
+        fail("input underflow");
+    }
+    return 0;
+}
+
 Memory
 InputReader::read_slow(size_t bytes)
 {
@@ -32,6 +39,9 @@ InputReader::read_slow(size_t bytes)
     if (_space.size() == bytes) {
         return Memory(&_space[0], _space.size());
     }
+    if (!failed()) {
+        fail("input underflow");
+    }
     return Memory();
 }
 
@@ -48,6 +58,7 @@ InputReader::fail(const vespalib::string &msg) {
         _data = Memory();
         _bytes_evicted += _pos;
         _pos = 0;
+        _eof = true;
     }
 }
 
diff --git a/vespalib/src/vespa/vespalib/data/input_reader.h b/vespalib/src/vespa/vespalib/data/input_reader.h
index 3d01eaffca0..38824f29139 100644
--- a/vespalib/src/vespa/vespalib/data/input_reader.h
+++ b/vespalib/src/vespa/vespalib/data/input_reader.h
@@ -23,6 +23,7 @@ private:
     Memory            _data;
     size_t            _pos;
     size_t            _bytes_evicted;
+    bool              _eof;
     vespalib::string  _error;
     std::vector<char> _space;
 
@@ -30,13 +31,15 @@ private:
     size_t size() const { return (_data.size - _pos); }
 
     size_t obtain_slow();
+    char read_slow();
     Memory read_slow(size_t bytes);
 
 public:
     explicit InputReader(Input &input)
-        : _input(input), _data(), _pos(0), _bytes_evicted(0), _error(), _space() {}
+        : _input(input), _data(), _pos(0), _bytes_evicted(0), _eof(false), _error(), _space() {}
     ~InputReader();
 
+    bool eof() const { return _eof; }
     bool failed() const { return !_error.empty(); }
     const vespalib::string &get_error_message() const { return _error; }
     size_t get_offset() const { return (_bytes_evicted + _pos); }
@@ -47,11 +50,11 @@ public:
      * Make sure we have more input data available.
      *
      * @return number of bytes available without requesting more from
-     *         the underlying Input. Returns 0 if and only is there is
+     *         the underlying Input. Returns 0 if and only if there is
      *         no more input data available.
      **/
     size_t obtain() {
-        if (__builtin_expect(_pos < _data.size, true)) {                    
+        if (__builtin_expect((_pos < _data.size) || _eof, true)) {
             return size();
         }
         return obtain_slow();
@@ -68,7 +71,7 @@ public:
         if (__builtin_expect(obtain() > 0, true)) {
             return _data.data[_pos++];
         }
-        return 0;
+        return read_slow();
     }
 
     /**