From 9c91901e8e57fd6366fd966e754a62a8a205c000 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Fri, 23 Apr 2010 10:04:42 +0200 Subject: erts: Implement recv_mark/1 and recv_set/1 for real The recv_mark/1 instruction will both save the current position in the message queue and a mark (the address of the loop_rec/2 instruction just following the recv_set/1 instruction). The recv_mark/1 instruction will only use the saved position if the mark is correct. The reason for saving and verifying the mark is that the compiler does not need to guarantee that no other receive instruction can be executed in between the recv_mark/1 and recv_set/1 instructions (the mark will be cleared by the remove_message/0 instruction when a message is removed from the message queue). That means that arbitrary function calls in between those instruction can be allowed. --- erts/emulator/beam/erl_message.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'erts/emulator/beam/erl_message.h') diff --git a/erts/emulator/beam/erl_message.h b/erts/emulator/beam/erl_message.h index 459c6363aa..489dee7b37 100644 --- a/erts/emulator/beam/erl_message.h +++ b/erts/emulator/beam/erl_message.h @@ -75,6 +75,13 @@ typedef struct { ErlMessage** last; /* point to the last next pointer */ ErlMessage** save; int len; /* queue length */ + + /* + * The following two fields are used by the recv_mark/1 and + * recv_set/1 instructions. + */ + BeamInstr* mark; /* address to rec_loop/2 instruction */ + ErlMessage** saved_last; /* saved last pointer */ } ErlMessageQueue; #ifdef ERTS_SMP @@ -137,6 +144,7 @@ do { \ (p)->msg.len--; \ if (__mp == NULL) \ (p)->msg.last = (p)->msg.save; \ + (p)->msg.mark = 0; \ } while(0) /* Reset message save point (after receive match) */ -- cgit v1.2.3