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-rw-r--r--Makefile.am2
-rw-r--r--src/util/CircularBuffer.hxx165
-rw-r--r--test/TestCircularBuffer.hxx141
-rw-r--r--test/test_util.cxx2
4 files changed, 310 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am
index 700511338..42b4169ec 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -362,6 +362,7 @@ libutil_a_SOURCES = \
src/util/DynamicFifoBuffer.hxx \
src/util/ConstBuffer.hxx \
src/util/WritableBuffer.hxx \
+ src/util/CircularBuffer.hxx \
src/util/LazyRandomEngine.cxx src/util/LazyRandomEngine.hxx \
src/util/SliceBuffer.hxx \
src/util/HugeAllocator.cxx src/util/HugeAllocator.hxx \
@@ -1832,6 +1833,7 @@ test_run_inotify_LDADD = \
endif
test_test_util_SOURCES = \
+ test/TestCircularBuffer.hxx \
test/test_util.cxx
test_test_util_CPPFLAGS = $(AM_CPPFLAGS) $(CPPUNIT_CFLAGS) -DCPPUNIT_HAVE_RTTI=0
test_test_util_CXXFLAGS = $(AM_CXXFLAGS) -Wno-error=deprecated-declarations
diff --git a/src/util/CircularBuffer.hxx b/src/util/CircularBuffer.hxx
new file mode 100644
index 000000000..60b6b3337
--- /dev/null
+++ b/src/util/CircularBuffer.hxx
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2014 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CIRCULAR_BUFFER_HPP
+#define CIRCULAR_BUFFER_HPP
+
+#include "WritableBuffer.hxx"
+
+#include <assert.h>
+#include <stddef.h>
+
+/**
+ * A circular buffer.
+ *
+ * This class does not manage buffer memory. It will not allocate or
+ * free any memory, it only manages the contents of an existing
+ * buffer given to the constructor.
+ *
+ * Everything between #head and #tail is valid data (may wrap around).
+ * If both are equal, then the buffer is empty. Due to this
+ * implementation detail, the buffer is empty when #size-1 items are
+ * stored; the last buffer cell cannot be used.
+ */
+template<typename T>
+class CircularBuffer {
+public:
+ typedef WritableBuffer<T> Range;
+ typedef typename Range::pointer_type pointer_type;
+ typedef typename Range::size_type size_type;
+
+protected:
+ /**
+ * The next index to be read.
+ */
+ size_type head;
+
+ /**
+ * The next index to be written to.
+ */
+ size_type tail;
+
+ const size_type size;
+ const pointer_type data;
+
+public:
+ constexpr CircularBuffer(pointer_type _data, size_type _size)
+ :head(0), tail(0), size(_size), data(_data) {}
+
+ CircularBuffer(const CircularBuffer &other) = delete;
+
+protected:
+ constexpr size_type Next(size_type i) const {
+ return i + 1 == size
+ ? 0
+ : i + 1;
+ }
+
+public:
+ void Clear() {
+ head = tail = 0;
+ }
+
+ size_type GetSize() const {
+ return size;
+ }
+
+ constexpr bool IsEmpty() const {
+ return head == tail;
+ }
+
+ constexpr bool IsFull() const {
+ return Next(tail) == head;
+ }
+
+ /**
+ * Prepares writing. Returns a buffer range which may be written.
+ * When you are finished, call Append().
+ */
+ Range Write() {
+ assert(head < size);
+ assert(tail < size);
+
+ size_type end = tail < head
+ ? head - 1
+ /* the "head==0" is there so we don't write
+ the last cell, as this situation cannot be
+ represented by head/tail */
+ : size - (head == 0);
+
+ return Range(data + tail, end - tail);
+ }
+
+ /**
+ * Expands the tail of the buffer, after data has been written
+ * to the buffer returned by Write().
+ */
+ void Append(size_type n) {
+ assert(head < size);
+ assert(tail < size);
+ assert(n < size);
+ assert(tail + n <= size);
+ assert(head <= tail || tail + n < head);
+
+ tail += n;
+
+ if (tail == size) {
+ assert(head > 0);
+ tail = 0;
+ }
+ }
+
+ /**
+ * Return a buffer range which may be read. The buffer pointer is
+ * writable, to allow modifications while parsing.
+ */
+ Range Read() {
+ assert(head < size);
+ assert(tail < size);
+
+ return Range(data + head, (tail < head ? size : tail) - head);
+ }
+
+ /**
+ * Marks a chunk as consumed.
+ */
+ void Consume(size_type n) {
+ assert(head < size);
+ assert(tail < size);
+ assert(n < size);
+ assert(head + n <= size);
+ assert(tail < head || head + n <= tail);
+
+ head += n;
+ if (head == size)
+ head = 0;
+ }
+};
+
+#endif
diff --git a/test/TestCircularBuffer.hxx b/test/TestCircularBuffer.hxx
new file mode 100644
index 000000000..e4285484b
--- /dev/null
+++ b/test/TestCircularBuffer.hxx
@@ -0,0 +1,141 @@
+/*
+ * Unit tests for class CircularBuffer.
+ */
+
+#include "config.h"
+#include "util/CircularBuffer.hxx"
+
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/TestFactoryRegistry.h>
+#include <cppunit/ui/text/TestRunner.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <string.h>
+#include <stdlib.h>
+
+class TestCircularBuffer : public CppUnit::TestFixture {
+ CPPUNIT_TEST_SUITE(TestCircularBuffer);
+ CPPUNIT_TEST(TestIt);
+ CPPUNIT_TEST_SUITE_END();
+
+public:
+ void TestIt() {
+ static size_t N = 8;
+ int data[N];
+ CircularBuffer<int> buffer(data, N);
+
+ /* '.' = empty; 'O' = occupied; 'X' = blocked */
+
+ /* checks on empty buffer */
+ /* [.......X] */
+ CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Write().size);
+
+ /* append one element */
+ /* [O......X] */
+ buffer.Append(1);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.Write().size);
+
+ /* append 6 elements, buffer is now full */
+ /* [OOOOOOOX] */
+ buffer.Append(6);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+ /* consume [0]; can append one at [7] */
+ /* [XOOOOOO.] */
+ buffer.Consume(1);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[7], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Write().size);
+
+ /* append one element; [0] is still empty but cannot
+ be written to because head==1 */
+ /* [XOOOOOOO] */
+ buffer.Append(1);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+ /* consume [1..3]; can append [0..2] */
+ /* [...XOOOO] */
+ buffer.Consume(3);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.Write().size);
+
+ /* append [0..1] */
+ /* [OO.XOOOO] */
+ buffer.Append(2);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[2], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Write().size);
+
+ /* append [2] */
+ /* [OOOXOOOO] */
+ buffer.Append(1);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
+
+ /* consume [4..7] */
+ /* [OOO....X] */
+ buffer.Consume(4);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.Read().size);
+ CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[3], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Write().size);
+
+ /* consume [0..2]; after that, we can only write 5,
+ because the CircularBuffer class doesn't have
+ special code to rewind/reset an empty buffer */
+ /* [..X.....] */
+ buffer.Consume(3);
+ CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+ CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
+ CPPUNIT_ASSERT_EQUAL(&data[3], buffer.Write().data);
+ CPPUNIT_ASSERT_EQUAL(size_t(5), buffer.Write().size);
+ }
+};
diff --git a/test/test_util.cxx b/test/test_util.cxx
index 07bcacbe9..aaadec68f 100644
--- a/test/test_util.cxx
+++ b/test/test_util.cxx
@@ -4,6 +4,7 @@
#include "config.h"
#include "util/UriUtil.hxx"
+#include "TestCircularBuffer.hxx"
#include <cppunit/TestFixture.h>
#include <cppunit/extensions/TestFactoryRegistry.h>
@@ -50,6 +51,7 @@ public:
};
CPPUNIT_TEST_SUITE_REGISTRATION(UriUtilTest);
+CPPUNIT_TEST_SUITE_REGISTRATION(TestCircularBuffer);
int
main(gcc_unused int argc, gcc_unused char **argv)
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-26 00:05:44 +0000