src/ipc/mem/PagePool.cc

   1 /*
   2  * $Id$
   3  *
   4  * DEBUG: section 54    Interprocess Communication
   5  *
   6  */
   7
   8 #include "config.h"
   9 #include "base/TextException.h"
  10 #include "ipc/mem/Page.h"
  11 #include "ipc/mem/PagePool.h"
  12
  13
  14 static String
  15 PageIndexId(String id)
  16 {
  17     id.append("-index");
  18     return id;
  19 }
  20
  21
  22 // Ipc::Mem::PagePool
  23
  24 Ipc::Mem::PagePool::PagePool(const String &id, const unsigned int capacity, const size_t pageSize):
  25     pageIndex(PageIndexId(id), capacity),
  26     shm(id.termedBuf())
  27 {
  28     shm.create(Shared::MemSize(capacity, pageSize));
  29     assert(shm.mem());
  30     shared = new (shm.mem()) Shared(capacity, pageSize);
  31 }
  32
  33 Ipc::Mem::PagePool::PagePool(const String &id):
  34     pageIndex(PageIndexId(id)), shm(id.termedBuf())
  35 {
  36     shm.open();
  37     shared = reinterpret_cast<Shared *>(shm.mem());
  38     assert(shared);
  39 }
  40
  41 void
  42 Ipc::Mem::PagePool::Unlink(const String &id)
  43 {
  44     PageStack::Unlink(PageIndexId(id));
  45     Segment::Unlink(id.termedBuf());
  46 }
  47
  48 bool
  49 Ipc::Mem::PagePool::get(PageId &page)
  50 {
  51     if (pageIndex.pop(page.number)) {
  52         page.pool = shared->theId;
  53         return true;
  54     }
  55     return false;
  56 }
  57
  58 void
  59 Ipc::Mem::PagePool::put(PageId &page)
  60 {
  61     Must(pageIdIsValid(page));
  62     pageIndex.push(page.number);
  63     page = PageId();
  64 }
  65
  66 void *
  67 Ipc::Mem::PagePool::pagePointer(const PageId &page)
  68 {
  69     Must(pageIdIsValid(page));
  70     return shared->theBuf + shared->thePageSize * (page.number - 1);
  71 }
  72
  73 bool
  74 Ipc::Mem::PagePool::pageIdIsValid(const PageId &page) const
  75 {
  76     return page.pool == shared->theId &&
  77         0 < page.number && page.number <= shared->theCapacity;
  78 }
  79
  80
  81 // Ipc::Mem::PagePool::Shared
  82
  83 static unsigned int LastPagePoolId = 0;
  84
  85 Ipc::Mem::PagePool::Shared::Shared(const unsigned int aCapacity, size_t aPageSize):
  86     theId(++LastPagePoolId), theCapacity(aCapacity), thePageSize(aPageSize)
  87 {
  88     if (LastPagePoolId + 1 == 0)
  89         ++LastPagePoolId; // skip zero pool id
  90 }
  91
  92 off_t
  93 Ipc::Mem::PagePool::Shared::MemSize(const unsigned int capacity, const size_t pageSize)
  94 {
  95     return static_cast<off_t>(sizeof(Shared)) +
  96         static_cast<off_t>(pageSize) * capacity;
  97 }