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-rw-r--r--erts/preloaded/src/erts_code_purger.erl283
1 files changed, 280 insertions, 3 deletions
diff --git a/erts/preloaded/src/erts_code_purger.erl b/erts/preloaded/src/erts_code_purger.erl
index 1ef4d096b7..6bb6e4fcdc 100644
--- a/erts/preloaded/src/erts_code_purger.erl
+++ b/erts/preloaded/src/erts_code_purger.erl
@@ -22,11 +22,288 @@
%% Purpose : Implement system process erts_code_purger
%% to handle code module purging.
--export([start/0]).
+-export([start/0, purge/1, soft_purge/1]).
-spec start() -> term().
start() ->
- receive M ->
+ register(erts_code_purger, self()),
+ process_flag(trap_exit, true),
+ loop().
+
+loop() ->
+ receive
+ {purge,Mod,From,Ref} when is_atom(Mod), is_pid(From) ->
+ Res = do_purge(Mod),
+ From ! {reply, purge, Res, Ref};
+
+ {soft_purge,Mod,From,Ref} when is_atom(Mod), is_pid(From) ->
+ Res = do_soft_purge(Mod),
+ From ! {reply, soft_purge, Res, Ref};
+
+ M ->
erlang:display({"erts_code_purger got msg", M})
end,
- start().
+ loop().
+
+
+%% purge(Module)
+%% Kill all processes running code from *old* Module, and then purge the
+%% module. Return {WasOld, DidKill}:
+%% {false, false} there was no old module to purge
+%% {true, false} module purged, no process killed
+%% {true, true} module purged, at least one process killed
+
+purge(Mod) when is_atom(Mod) ->
+ Ref = make_ref(),
+ erts_code_purger ! {purge, Mod, self(), Ref},
+ receive
+ {reply, purge, Result, Ref} ->
+ Result
+ end.
+
+
+do_purge(Mod) ->
+ case erlang:check_old_code(Mod) of
+ false ->
+ {false, false};
+ true ->
+ true = erlang:copy_literals(Mod, true),
+ DidKill = check_proc_code(erlang:processes(), Mod, true),
+ true = erlang:copy_literals(Mod, false),
+ try
+ erlang:purge_module(Mod)
+ catch
+ _:_ -> ignore
+ end,
+ {true, DidKill}
+ end.
+
+%% soft_purge(Module)
+%% Purge old code only if no procs remain that run old code.
+%% Return true in that case, false if procs remain (in this
+%% case old code is not purged)
+
+soft_purge(Mod) ->
+ Ref = make_ref(),
+ erts_code_purger ! {soft_purge, Mod, self(), Ref},
+ receive
+ {reply, soft_purge, Result, Ref} ->
+ Result
+ end.
+
+
+do_soft_purge(Mod) ->
+ case erlang:check_old_code(Mod) of
+ false ->
+ true;
+ true ->
+ true = erlang:copy_literals(Mod, true),
+ case check_proc_code(erlang:processes(), Mod, false) of
+ false ->
+ true = erlang:copy_literals(Mod, false),
+ false;
+ true ->
+ true = erlang:copy_literals(Mod, false),
+ try
+ erlang:purge_module(Mod)
+ catch
+ _:_ -> ignore
+ end,
+ true
+ end
+ end.
+
+%%
+%% check_proc_code(Pids, Mod, Hard) - Send asynchronous
+%% requests to all processes to perform a check_process_code
+%% operation. Each process will check their own state and
+%% reply with the result. If 'Hard' equals
+%% - true, processes that refer 'Mod' will be killed. If
+%% any processes were killed true is returned; otherwise,
+%% false.
+%% - false, and any processes refer 'Mod', false will
+%% returned; otherwise, true.
+%%
+%% Requests will be sent to all processes identified by
+%% Pids at once, but without allowing GC to be performed.
+%% Check process code operations that are aborted due to
+%% GC need, will be restarted allowing GC. However, only
+%% ?MAX_CPC_GC_PROCS outstanding operation allowing GC at
+%% a time will be allowed. This in order not to blow up
+%% memory wise.
+%%
+%% We also only allow ?MAX_CPC_NO_OUTSTANDING_KILLS
+%% outstanding kills. This both in order to avoid flooding
+%% our message queue with 'DOWN' messages and limiting the
+%% amount of memory used to keep references to all
+%% outstanding kills.
+%%
+
+%% We maybe should allow more than two outstanding
+%% GC requests, but for now we play it safe...
+-define(MAX_CPC_GC_PROCS, 2).
+-define(MAX_CPC_NO_OUTSTANDING_KILLS, 10).
+
+-record(cpc_static, {hard, module, tag}).
+
+-record(cpc_kill, {outstanding = [],
+ no_outstanding = 0,
+ waiting = [],
+ killed = false}).
+
+check_proc_code(Pids, Mod, Hard) ->
+ Tag = erlang:make_ref(),
+ CpcS = #cpc_static{hard = Hard,
+ module = Mod,
+ tag = Tag},
+ check_proc_code(CpcS, cpc_init(CpcS, Pids, 0), 0, [], #cpc_kill{}, true).
+
+check_proc_code(#cpc_static{hard = true}, 0, 0, [],
+ #cpc_kill{outstanding = [], waiting = [], killed = Killed},
+ true) ->
+ %% No outstanding requests. We did a hard check, so result is whether or
+ %% not we killed any processes...
+ Killed;
+check_proc_code(#cpc_static{hard = false}, 0, 0, [], _KillState, Success) ->
+ %% No outstanding requests and we did a soft check...
+ Success;
+check_proc_code(#cpc_static{hard = false, tag = Tag} = CpcS, NoReq0, NoGcReq0,
+ [], _KillState, false) ->
+ %% Failed soft check; just cleanup the remaining replies corresponding
+ %% to the requests we've sent...
+ {NoReq1, NoGcReq1} = receive
+ {check_process_code, {Tag, _P, GC}, _Res} ->
+ case GC of
+ false -> {NoReq0-1, NoGcReq0};
+ true -> {NoReq0, NoGcReq0-1}
+ end
+ end,
+ check_proc_code(CpcS, NoReq1, NoGcReq1, [], _KillState, false);
+check_proc_code(#cpc_static{tag = Tag} = CpcS, NoReq0, NoGcReq0, NeedGC0,
+ KillState0, Success) ->
+
+ %% Check if we should request a GC operation
+ {NoGcReq1, NeedGC1} = case NoGcReq0 < ?MAX_CPC_GC_PROCS of
+ GcOpAllowed when GcOpAllowed == false;
+ NeedGC0 == [] ->
+ {NoGcReq0, NeedGC0};
+ _ ->
+ {NoGcReq0+1, cpc_request_gc(CpcS,NeedGC0)}
+ end,
+
+ %% Wait for a cpc reply or 'DOWN' message
+ {NoReq1, NoGcReq2, Pid, Result, KillState1} = cpc_recv(Tag,
+ NoReq0,
+ NoGcReq1,
+ KillState0),
+
+ %% Check the result of the reply
+ case Result of
+ aborted ->
+ %% Operation aborted due to the need to GC in order to
+ %% determine if the process is referring the module.
+ %% Schedule the operation for restart allowing GC...
+ check_proc_code(CpcS, NoReq1, NoGcReq2, [Pid|NeedGC1], KillState1,
+ Success);
+ false ->
+ %% Process not referring the module; done with this process...
+ check_proc_code(CpcS, NoReq1, NoGcReq2, NeedGC1, KillState1,
+ Success);
+ true ->
+ %% Process referring the module...
+ case CpcS#cpc_static.hard of
+ false ->
+ %% ... and soft check. The whole operation failed so
+ %% no point continuing; clean up and fail...
+ check_proc_code(CpcS, NoReq1, NoGcReq2, [], KillState1,
+ false);
+ true ->
+ %% ... and hard check; schedule kill of it...
+ check_proc_code(CpcS, NoReq1, NoGcReq2, NeedGC1,
+ cpc_sched_kill(Pid, KillState1), Success)
+ end;
+ 'DOWN' ->
+ %% Handled 'DOWN' message
+ check_proc_code(CpcS, NoReq1, NoGcReq2, NeedGC1,
+ KillState1, Success)
+ end.
+
+cpc_recv(Tag, NoReq, NoGcReq, #cpc_kill{outstanding = []} = KillState) ->
+ receive
+ {check_process_code, {Tag, Pid, GC}, Res} ->
+ cpc_handle_cpc(NoReq, NoGcReq, GC, Pid, Res, KillState)
+ end;
+cpc_recv(Tag, NoReq, NoGcReq,
+ #cpc_kill{outstanding = [R0, R1, R2, R3, R4 | _]} = KillState) ->
+ receive
+ {'DOWN', R, process, _, _} when R == R0;
+ R == R1;
+ R == R2;
+ R == R3;
+ R == R4 ->
+ cpc_handle_down(NoReq, NoGcReq, R, KillState);
+ {check_process_code, {Tag, Pid, GC}, Res} ->
+ cpc_handle_cpc(NoReq, NoGcReq, GC, Pid, Res, KillState)
+ end;
+cpc_recv(Tag, NoReq, NoGcReq, #cpc_kill{outstanding = [R|_]} = KillState) ->
+ receive
+ {'DOWN', R, process, _, _} ->
+ cpc_handle_down(NoReq, NoGcReq, R, KillState);
+ {check_process_code, {Tag, Pid, GC}, Res} ->
+ cpc_handle_cpc(NoReq, NoGcReq, GC, Pid, Res, KillState)
+ end.
+
+cpc_handle_down(NoReq, NoGcReq, R, #cpc_kill{outstanding = Rs,
+ no_outstanding = N} = KillState) ->
+ {NoReq, NoGcReq, undefined, 'DOWN',
+ cpc_sched_kill_waiting(KillState#cpc_kill{outstanding = cpc_list_rm(R, Rs),
+ no_outstanding = N-1})}.
+
+cpc_list_rm(R, [R|Rs]) ->
+ Rs;
+cpc_list_rm(R0, [R1|Rs]) ->
+ [R1|cpc_list_rm(R0, Rs)].
+
+cpc_handle_cpc(NoReq, NoGcReq, false, Pid, Res, KillState) ->
+ {NoReq-1, NoGcReq, Pid, Res, KillState};
+cpc_handle_cpc(NoReq, NoGcReq, true, Pid, Res, KillState) ->
+ {NoReq, NoGcReq-1, Pid, Res, KillState}.
+
+cpc_sched_kill_waiting(#cpc_kill{waiting = []} = KillState) ->
+ KillState;
+cpc_sched_kill_waiting(#cpc_kill{outstanding = Rs,
+ no_outstanding = N,
+ waiting = [P|Ps]} = KillState) ->
+ R = erlang:monitor(process, P),
+ exit(P, kill),
+ KillState#cpc_kill{outstanding = [R|Rs],
+ no_outstanding = N+1,
+ waiting = Ps,
+ killed = true}.
+
+cpc_sched_kill(Pid, #cpc_kill{no_outstanding = N, waiting = Pids} = KillState)
+ when N >= ?MAX_CPC_NO_OUTSTANDING_KILLS ->
+ KillState#cpc_kill{waiting = [Pid|Pids]};
+cpc_sched_kill(Pid,
+ #cpc_kill{outstanding = Rs, no_outstanding = N} = KillState) ->
+ R = erlang:monitor(process, Pid),
+ exit(Pid, kill),
+ KillState#cpc_kill{outstanding = [R|Rs],
+ no_outstanding = N+1,
+ killed = true}.
+
+cpc_request(#cpc_static{tag = Tag, module = Mod}, Pid, AllowGc) ->
+ erlang:check_process_code(Pid, Mod, [{async, {Tag, Pid, AllowGc}},
+ {allow_gc, AllowGc}]).
+
+cpc_request_gc(CpcS, [Pid|Pids]) ->
+ cpc_request(CpcS, Pid, true),
+ Pids.
+
+cpc_init(_CpcS, [], NoReqs) ->
+ NoReqs;
+cpc_init(CpcS, [Pid|Pids], NoReqs) ->
+ cpc_request(CpcS, Pid, false),
+ cpc_init(CpcS, Pids, NoReqs+1).
+
+% end of check_proc_code() implementation.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 13:22:51 +0000