Add basic tracing functionality

lib/common/compiler.h

@@ -90,6 +90,7 @@
 #  endif
 #endif
 
+
 /* target attribute */
 #ifndef __has_attribute
   #define __has_attribute(x) 0  /* Compatibility with non-clang compilers. */

lib/common/zstd_trace.c

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2016-2021, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include "zstd_trace.h"
+#include "../zstd.h"
+
+#include "compiler.h"
+
+#if ZSTD_TRACE && ZSTD_HAVE_WEAK_SYMBOLS
+
+ZSTD_WEAK_ATTR int ZSTD_trace_compress_begin(ZSTD_CCtx const* cctx)
+{
+    (void)cctx;
+    return 0;
+}
+
+ZSTD_WEAK_ATTR void ZSTD_trace_compress_end(ZSTD_CCtx const* cctx, ZSTD_trace const* trace)
+{
+    (void)cctx;
+    (void)trace;
+}
+
+ZSTD_WEAK_ATTR int ZSTD_trace_decompress_begin(ZSTD_DCtx const* dctx)
+{
+    (void)dctx;
+    return 0;
+}
+
+ZSTD_WEAK_ATTR void ZSTD_trace_decompress_end(ZSTD_DCtx const* dctx, ZSTD_trace const* trace)
+{
+    (void)dctx;
+    (void)trace;
+}
+
+#endif

lib/common/zstd_trace.h

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2016-2021, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#ifndef ZSTD_TRACE_H
+#define ZSTD_TRACE_H
+
+#include <stddef.h>
+
+/* weak symbol support */
+#if !defined(ZSTD_HAVE_WEAK_SYMBOLS) && defined(__GNUC__) && \
+    !defined(__APPLE__) && !defined(_WIN32) && !defined(__MINGW32__) && \
+    !defined(__CYGWIN__)
+#  define ZSTD_HAVE_WEAK_SYMBOLS 1
+#else
+#  define ZSTD_HAVE_WEAK_SYMBOLS 0
+#endif
+#if ZSTD_HAVE_WEAK_SYMBOLS
+#  define ZSTD_WEAK_ATTR __attribute__((__weak__))
+#else
+#  define ZSTD_WEAK_ATTR
+#endif
+
+/* Only enable tracing when weak symbols are available. */
+#ifndef ZSTD_TRACE
+#  define ZSTD_TRACE ZSTD_HAVE_WEAK_SYMBOLS
+#endif
+
+#if ZSTD_TRACE
+
+struct ZSTD_CCtx_s;
+struct ZSTD_DCtx_s;
+struct ZSTD_CCtx_params_s;
+
+typedef struct {
+    /**
+     * ZSTD_VERSION_NUMBER
+     *
+     * This is guaranteed to be the first member of ZSTD_trace.
+     * Otherwise, this struct is not stable between versions. If
+     * the version number does not match your expectation, you
+     * should not interpret the rest of the struct.
+     */
+    unsigned version;
+    /**
+     * Non-zero if streaming (de)compression is used.
+     */
+    unsigned streaming;
+    /**
+     * The dictionary ID.
+     */
+    unsigned dictionaryID;
+    /**
+     * Is the dictionary cold?
+     * Only set on decompression.
+     */
+    unsigned dictionaryIsCold;
+    /**
+     * The dictionary size or zero if no dictionary.
+     */
+    size_t dictionarySize;
+    /**
+     * The uncompressed size of the data.
+     */
+    size_t uncompressedSize;
+    /**
+     * The compressed size of the data.
+     */
+    size_t compressedSize;
+    /**
+     * The fully resolved CCtx parameters (NULL on decompression).
+     */
+    struct ZSTD_CCtx_params_s const* params;
+} ZSTD_trace;
+
+/**
+ * Trace the beginning of a compression call.
+ * @param cctx The dctx pointer for the compression.
+ *             It can be used as a key to map begin() to end().
+ * @returns Non-zero if tracing is enabled.
+ */
+int ZSTD_trace_compress_begin(struct ZSTD_CCtx_s const* cctx);
+
+/**
+ * Trace the end of a compression call.
+ * @param cctx The dctx pointer for the decompression.
+ * @param trace The zstd tracing info.
+ */
+void ZSTD_trace_compress_end(
+    struct ZSTD_CCtx_s const* cctx,
+    ZSTD_trace const* trace);
+
+/**
+ * Trace the beginning of a decompression call.
+ * @param dctx The dctx pointer for the decompression.
+ *             It can be used as a key to map begin() to end().
+ * @returns Non-zero if tracing is enabled.
+ */
+int ZSTD_trace_decompress_begin(struct ZSTD_DCtx_s const* dctx);
+
+/**
+ * Trace the end of a decompression call.
+ * @param dctx The dctx pointer for the decompression.
+ * @param trace The zstd tracing info.
+ */
+void ZSTD_trace_decompress_end(
+    struct ZSTD_DCtx_s const* dctx,
+    ZSTD_trace const* trace);
+
+#endif /* ZSTD_TRACE */
+
+#endif /* ZSTD_TRACE_H */