src/ipc/mem/PagePool.cc

   1 /*
   2  * Copyright (C) 1996-2025 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 shmId, const Ipc::Mem::PoolId stackId, const unsigned int capacity, const size_t pageSize)
  20 {
  21     PageStack::Config config;
  22     config.poolId = stackId;
  23     config.pageSize = pageSize; // the pages are stored in Ipc::Mem::Pages
  24     config.capacity = capacity;
  25     config.createFull = true; // all pages are initially available
  26     return shm_new(PageStack)(shmId, config);
  27 }
  28
  29 Ipc::Mem::PagePool::PagePool(const char *const id):
  30     pageIndex(shm_old(PageStack)(id)),
  31     theLevels(reinterpret_cast<Levels_t *>(
  32                   reinterpret_cast<char *>(pageIndex.getRaw()) +
  33                   pageIndex->stackSize() + pageIndex->levelsPaddingSize())),
  34     theBuf(reinterpret_cast<char *>(theLevels + PageId::maxPurpose))
  35 {
  36 }
  37
  38 size_t
  39 Ipc::Mem::PagePool::level(const int purpose) const
  40 {
  41     Must(0 <= purpose && purpose < PageId::maxPurpose);
  42     return theLevels[purpose];
  43 }
  44
  45 bool
  46 Ipc::Mem::PagePool::get(const PageId::Purpose purpose, PageId &page)
  47 {
  48     Must(0 <= purpose && purpose < PageId::maxPurpose);
  49     if (pageIndex->pop(page)) {
  50         page.purpose = purpose;
  51         ++theLevels[purpose];
  52         return true;
  53     }
  54     return false;
  55 }
  56
  57 void
  58 Ipc::Mem::PagePool::put(PageId &page)
  59 {
  60     if (!page)
  61         return;
  62
  63     Must(0 <= page.purpose && page.purpose < PageId::maxPurpose);
  64     --theLevels[page.purpose];
  65     page.purpose = PageId::maxPurpose;
  66     return pageIndex->push(page);
  67 }
  68
  69 char *
  70 Ipc::Mem::PagePool::pagePointer(const PageId &page)
  71 {
  72     Must(pageIndex->pageIdIsValid(page));
  73     return theBuf + pageSize() * (page.number - 1);
  74 }
  75