| // Copyright (c) 2008, Google Inc. |
| // All rights reserved. |
| // |
| // 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. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // 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 COPYRIGHT |
| // OWNER 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. |
| |
| // --- |
| // Author: Sanjay Ghemawat <opensource@google.com> |
| // |
| // A Span is a contiguous run of pages. |
| |
| #ifndef TCMALLOC_SPAN_H_ |
| #define TCMALLOC_SPAN_H_ |
| |
| #include <config.h> |
| #include "common.h" |
| |
| namespace tcmalloc { |
| |
| // Information kept for a span (a contiguous run of pages). |
| struct Span { |
| PageID start; // Starting page number |
| Length length; // Number of pages in span |
| Span* next; // Used when in link list |
| Span* prev; // Used when in link list |
| void* objects; // Linked list of free objects |
| unsigned int refcount : 16; // Number of non-free objects |
| unsigned int sizeclass : 8; // Size-class for small objects (or 0) |
| unsigned int location : 2; // Is the span on a freelist, and if so, which? |
| unsigned int sample : 1; // Sampled object? |
| |
| #undef SPAN_HISTORY |
| #ifdef SPAN_HISTORY |
| // For debugging, we can keep a log events per span |
| int nexthistory; |
| char history[64]; |
| int value[64]; |
| #endif |
| |
| // What freelist the span is on: IN_USE if on none, or normal or returned |
| enum { IN_USE, ON_NORMAL_FREELIST, ON_RETURNED_FREELIST }; |
| }; |
| |
| #ifdef SPAN_HISTORY |
| void Event(Span* span, char op, int v = 0); |
| #else |
| #define Event(s,o,v) ((void) 0) |
| #endif |
| |
| // Allocator/deallocator for spans |
| Span* NewSpan(PageID p, Length len); |
| void DeleteSpan(Span* span); |
| |
| // ------------------------------------------------------------------------- |
| // Doubly linked list of spans. |
| // ------------------------------------------------------------------------- |
| |
| // Initialize *list to an empty list. |
| void DLL_Init(Span* list); |
| |
| // Remove 'span' from the linked list in which it resides, updating the |
| // pointers of adjacent Spans and setting span's next and prev to NULL. |
| void DLL_Remove(Span* span); |
| |
| // Return true iff "list" is empty. |
| inline bool DLL_IsEmpty(const Span* list) { |
| return list->next == list; |
| } |
| |
| // Add span to the front of list. |
| void DLL_Prepend(Span* list, Span* span); |
| |
| // Return the length of the linked list. O(n) |
| int DLL_Length(const Span* list); |
| |
| } // namespace tcmalloc |
| |
| #endif // TCMALLOC_SPAN_H_ |
