PagePool.cc
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1 /*
2  * Copyright (C) 1996-2022 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 
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
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
59 {
60  if (!page)
61  return;
62 
63  Must(0 <= page.purpose && page.purpose < PageId::maxPurpose);
64  --theLevels[page.purpose];
66  return pageIndex->push(page);
67 }
68 
69 char *
71 {
72  Must(pageIndex->pageIdIsValid(page));
73  return theBuf + pageSize() * (page.number - 1);
74 }
75 
#define shm_new(Class)
Definition: Pointer.h:200
#define shm_old(Class)
Definition: Pointer.h:201
#define Must(condition)
Definition: TextException.h:71
Shared memory page identifier, address, or handler.
Definition: Page.h:24
uint32_t number
page number within the segment
Definition: Page.h:42
Purpose purpose
page purpose
Definition: Page.h:45
char * pagePointer(const PageId &page)
converts page handler into a temporary writeable shared memory pointer
Definition: PagePool.cc:70
size_t pageSize() const
Definition: PagePool.h:35
PageStack::Levels_t Levels_t
Definition: PagePool.h:52
PagePool(const char *const id)
Definition: PagePool.cc:29
unsigned int capacity() const
Definition: PagePool.h:34
static Owner * Init(const char *const shmId, const Ipc::Mem::PoolId stackId, const unsigned int capacity, const size_t pageSize)
Definition: PagePool.cc:19
size_t level() const
approximate number of shared memory pages used now
Definition: PagePool.h:39
void put(PageId &page)
makes identified page available as a free page to future get() callers
Definition: PagePool.cc:58
bool get(const PageId::Purpose purpose, PageId &page)
sets page ID and returns true unless no free pages are found
Definition: PagePool.cc:46
PageStack construction and SharedMemorySize calculation parameters.
Definition: PageStack.h:123
PageCount capacity
the maximum number of pages
Definition: PageStack.h:127
uint32_t poolId
pool ID
Definition: PageStack.h:125
size_t pageSize
page size, used to calculate shared memory size
Definition: PageStack.h:126
bool createFull
whether a newly created PageStack should be prefilled with PageIds
Definition: PageStack.h:130
uint32_t PoolId
Definition: forward.h:17

 

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