libgo/runtime/chan.h

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 typedef struct  WaitQ   WaitQ;
   6 typedef struct  SudoG   SudoG;
   7 typedef struct  Select  Select;
   8 typedef struct  Scase   Scase;
   9
  10 typedef struct  __go_type_descriptor    Type;
  11 typedef struct  __go_channel_type       ChanType;
  12
  13 struct  SudoG
  14 {
  15         G*      g;
  16         uint32* selectdone;
  17         SudoG*  link;
  18         int64   releasetime;
  19         byte*   elem;           // data element
  20 };
  21
  22 struct  WaitQ
  23 {
  24         SudoG*  first;
  25         SudoG*  last;
  26 };
  27
  28 // The garbage collector is assuming that Hchan can only contain pointers into the stack
  29 // and cannot contain pointers into the heap.
  30 struct  Hchan
  31 {
  32         uintgo  qcount;                 // total data in the q
  33         uintgo  dataqsiz;               // size of the circular q
  34         uint16  elemsize;
  35         uint16  pad;                    // ensures proper alignment of the buffer that follows Hchan in memory
  36         bool    closed;
  37         const Type* elemtype;           // element type
  38         uintgo  sendx;                  // send index
  39         uintgo  recvx;                  // receive index
  40         WaitQ   recvq;                  // list of recv waiters
  41         WaitQ   sendq;                  // list of send waiters
  42         Lock;
  43 };
  44
  45 // Buffer follows Hchan immediately in memory.
  46 // chanbuf(c, i) is pointer to the i'th slot in the buffer.
  47 #define chanbuf(c, i) ((byte*)((c)+1)+(uintptr)(c)->elemsize*(i))
  48
  49 enum
  50 {
  51         debug = 0,
  52
  53         // Scase.kind
  54         CaseRecv,
  55         CaseSend,
  56         CaseDefault,
  57 };
  58
  59 struct  Scase
  60 {
  61         SudoG   sg;                     // must be first member (cast to Scase)
  62         Hchan*  chan;                   // chan
  63         uint16  kind;
  64         uint16  index;                  // index to return
  65         bool*   receivedp;              // pointer to received bool (recv2)
  66 };
  67
  68 struct  Select
  69 {
  70         uint16  tcase;                  // total count of scase[]
  71         uint16  ncase;                  // currently filled scase[]
  72         uint16* pollorder;              // case poll order
  73         Hchan** lockorder;              // channel lock order
  74         Scase   scase[1];               // one per case (in order of appearance)
  75 };