src/ipc/mem/PagePool.cc

   1 /*
   2  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 54    Interprocess Communication */
  10
  11 #include "squid.h"
  12 #include "base/TextException.h"
  13 #include "ipc/mem/Page.h"
  14 #include "ipc/mem/PagePool.h"
  15
  16 // Ipc::Mem::PagePool
  17
  18 Ipc::Mem::PagePool::Owner *
  19 Ipc::Mem::PagePool::Init(const char *const id, const unsigned int capacity, const size_t pageSize)
  20 {
  21     static uint32_t LastPagePoolId = 0;
  22     if (++LastPagePoolId == 0)
  23         ++LastPagePoolId; // skip zero pool id
  24     return shm_new(PageStack)(id, LastPagePoolId, capacity, pageSize);
  25 }
  26
  27 Ipc::Mem::PagePool::PagePool(const char *const id):
  28     pageIndex(shm_old(PageStack)(id)),
  29     theLevels(reinterpret_cast<Atomic::Word *>(
  30                   reinterpret_cast<char *>(pageIndex.getRaw()) +
  31                   pageIndex->stackSize())),
  32     theBuf(reinterpret_cast<char *>(theLevels + PageId::maxPurpose))
  33 {
  34 }
  35
  36 size_t
  37 Ipc::Mem::PagePool::level(const int purpose) const
  38 {
  39     Must(0 <= purpose && purpose < PageId::maxPurpose);
  40     return theLevels[purpose];
  41 }
  42
  43 bool
  44 Ipc::Mem::PagePool::get(const PageId::Purpose purpose, PageId &page)
  45 {
  46     Must(0 <= purpose && purpose < PageId::maxPurpose);
  47     if (pageIndex->pop(page)) {
  48         page.purpose = purpose;
  49         ++theLevels[purpose];
  50         return true;
  51     }
  52     return false;
  53 }
  54
  55 void
  56 Ipc::Mem::PagePool::put(PageId &page)
  57 {
  58     if (!page)
  59         return;
  60
  61     Must(0 <= page.purpose && page.purpose < PageId::maxPurpose);
  62     --theLevels[page.purpose];
  63     page.purpose = PageId::maxPurpose;
  64     return pageIndex->push(page);
  65 }
  66
  67 char *
  68 Ipc::Mem::PagePool::pagePointer(const PageId &page)
  69 {
  70     Must(pageIndex->pageIdIsValid(page));
  71     return theBuf + pageSize() * (page.number - 1);
  72 }
  73