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author | Rickard Green <rickard@erlang.org> | 2016-01-13 18:33:42 +0100 |
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committer | Rickard Green <rickard@erlang.org> | 2016-01-20 11:10:37 +0100 |
commit | dc8e62f33ad0ca7a772ec74d67b6d3e157f639b4 (patch) | |
tree | dfb9c44328ba358c34678d557941a13b79e3d281 /lib/stdlib | |
parent | 858c6f7fa44f7b2dc363b359198d6522dd60e914 (diff) | |
download | otp-dc8e62f33ad0ca7a772ec74d67b6d3e157f639b4.tar.gz otp-dc8e62f33ad0ca7a772ec74d67b6d3e157f639b4.tar.bz2 otp-dc8e62f33ad0ca7a772ec74d67b6d3e157f639b4.zip |
Introduce time warp safe replacement for safe_fixed option
The new time warp safe option is safe_fixed_monotonic_time which
gives erlang:monotonic_time().
The safe_fixed option was also slightly changed. It now gives
erlang:timestamp() instead of erlang:now(). This has however
not been documented, so it is considered a compatible change.
The above effects both ets, and dets.
This commit also include the bugfix OTP-13239 for
dets:info(Tab, safe_fixed). The timestamp in the result returned
by dets:info(Tab, safe_fixed) was unintentionally broken as a
result of the time API rewrites in OTP 18.0.
Diffstat (limited to 'lib/stdlib')
-rw-r--r-- | lib/stdlib/doc/src/dets.xml | 31 | ||||
-rw-r--r-- | lib/stdlib/doc/src/ets.xml | 41 | ||||
-rw-r--r-- | lib/stdlib/src/dets.erl | 36 | ||||
-rw-r--r-- | lib/stdlib/src/ets.erl | 2 | ||||
-rw-r--r-- | lib/stdlib/src/stdlib.app.src | 2 | ||||
-rw-r--r-- | lib/stdlib/test/dets_SUITE.erl | 24 | ||||
-rw-r--r-- | lib/stdlib/test/ets_SUITE.erl | 35 |
7 files changed, 145 insertions, 26 deletions
diff --git a/lib/stdlib/doc/src/dets.xml b/lib/stdlib/doc/src/dets.xml index a0d3f95b6a..48400733d1 100644 --- a/lib/stdlib/doc/src/dets.xml +++ b/lib/stdlib/doc/src/dets.xml @@ -399,15 +399,40 @@ kept in RAM.</p> </item> <item> - <p><c>{safe_fixed,</c> SafeFixed<c>}</c>. If the table - is fixed, SafeFixed is a tuple <c>{FixedAtTime, [{Pid,RefCount}]}</c>. <c>FixedAtTime</c> is the time when + <p><c>{safe_fixed_monotonic_time, SafeFixed}</c>. If the table + is fixed, <c>SafeFixed</c> is a tuple <c>{FixedAtTime, [{Pid,RefCount}]}</c>. + <c>FixedAtTime</c> is the time when the table was first fixed, and <c>Pid</c> is the pid of the process that fixes the table <c>RefCount</c> times. There may be any number of processes in the list. If the table is not fixed, SafeFixed is the atom <c>false</c>.</p> + <p><c>FixedAtTime</c> will correspond to the result + returned by + <seealso marker="erts:erlang#monotonic_time/0">erlang:monotonic_time/0</seealso> + at the time of fixation. The usage of <c>safe_fixed_monotonic_time</c> is + <seealso marker="erts:time_correction#Time_Warp_Safe_Code">time warp + safe</seealso>.</p> </item> <item> - <p><c>{version, integer()</c>, the version of the format of + <p> + <c>{safe_fixed, SafeFixed}</c>. The same as + <c>{safe_fixed_monotonic_time, SafeFixed}</c> with the exception + of the format and value of <c>FixedAtTime</c>. + </p> + <p> + <c>FixedAtTime</c> will correspond to the result returned by + <seealso marker="erts:erlang#timestamp/0">erlang:timestamp/0</seealso> + at the time of fixation. Note that when the system is using + single or multi + <seealso marker="erts:time_correction#Time_Warp_Modes">time warp + modes</seealso> this might produce strange results. This + since the usage of <c>safe_fixed</c> is not + <seealso marker="erts:time_correction#Time_Warp_Safe_Code">time warp + safe</seealso>. Time warp safe code need to use + <c>safe_fixed_monotonic_time</c> instead.</p> + </item> + <item> + <p><c>{version, integer()}</c>, the version of the format of the table.</p> </item> </list> diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml index 7b01109ff8..447fe51130 100644 --- a/lib/stdlib/doc/src/ets.xml +++ b/lib/stdlib/doc/src/ets.xml @@ -488,14 +488,39 @@ Error: fun containing local Erlang function calls <item><c>Item=fixed, Value=boolean()</c> <br></br> Indicates if the table is fixed by any process or not.</item> - <item> - <p><c>Item=safe_fixed, Value={FirstFixed,Info}|false</c> <br></br> + <item><marker id="info_2_safe_fixed_monotonic_time"/> + <p><c>Item=safe_fixed|safe_fixed_monotonic_time, Value={FixationTime,Info}|false</c> <br></br> </p> - <p>If the table has been fixed using <c>safe_fixtable/2</c>, - the call returns a tuple where <c>FirstFixed</c> is the + <p>If the table has been fixed using + <seealso marker="#safe_fixtable/2"><c>safe_fixtable/2</c></seealso>, + the call returns a tuple where <c>FixationTime</c> is the time when the table was first fixed by a process, which may or may not be one of the processes it is fixed by right now.</p> + <p>The format and value of <c>FixationTime</c> depends on + <c>Item</c>:</p> + <taglist> + <tag><c>safe_fixed</c></tag> + <item><p><c>FixationTime</c> will correspond to the result + returned by + <seealso marker="erts:erlang#timestamp/0">erlang:timestamp/0</seealso> + at the time of fixation. Note that when the system is using + single or multi + <seealso marker="erts:time_correction#Time_Warp_Modes">time warp + modes</seealso> this might produce strange results. This + since the usage of <c>safe_fixed</c> is not + <seealso marker="erts:time_correction#Time_Warp_Safe_Code">time warp + safe</seealso>. Time warp safe code need to use + <c>safe_fixed_monotonic_time</c> instead.</p></item> + + <tag><c>safe_fixed_monotonic_time</c></tag> + <item><p><c>FixationTime</c> will correspond to the result + returned by + <seealso marker="erts:erlang#monotonic_time/0">erlang:monotonic_time/0</seealso> + at the time of fixation. The usage of <c>safe_fixed_monotonic_time</c> is + <seealso marker="erts:time_correction#Time_Warp_Safe_Code">time warp + safe</seealso>.</p></item> + </taglist> <p><c>Info</c> is a possibly empty lists of tuples <c>{Pid,RefCount}</c>, one tuple for every process the table is fixed by right now. <c>RefCount</c> is the value @@ -1135,9 +1160,11 @@ clean_all_with_value(Tab,X,Key) -> table but never releases it, the memory used by the deleted objects will never be freed. The performance of operations on the table will also degrade significantly.</p> - <p>Use <c>info/2</c> to retrieve information about which - processes have fixed which tables. A system with a lot of - processes fixing tables may need a monitor which sends alarms + <p>Use + <seealso marker="#info_2_safe_fixed_monotonic_time"><c>info(Tab, + safe_fixed_monotonic_time)</c></seealso> to retrieve information + about which processes have fixed which tables. A system with a lot + of processes fixing tables may need a monitor which sends alarms when tables have been fixed for too long.</p> <p>Note that for tables of the <c>ordered_set</c> type, <c>safe_fixtable/2</c> is not necessary as calls to diff --git a/lib/stdlib/src/dets.erl b/lib/stdlib/src/dets.erl index 6d07f4018a..2d037ff795 100644 --- a/lib/stdlib/src/dets.erl +++ b/lib/stdlib/src/dets.erl @@ -372,7 +372,7 @@ info(Tab) -> Item :: 'access' | 'auto_save' | 'bchunk_format' | 'hash' | 'file_size' | 'filename' | 'keypos' | 'memory' | 'no_keys' | 'no_objects' | 'no_slots' | 'owner' | 'ram_file' - | 'safe_fixed' | 'size' | 'type' | 'version', + | 'safe_fixed' | 'safe_fixed_monotonic_time' | 'size' | 'type' | 'version', Value :: term(). info(Tab, owner) -> @@ -1964,7 +1964,9 @@ do_safe_fixtable(Head, Pid, true) -> case Head#head.fixed of false -> link(Pid), - Fixed = {utime_now(), [{Pid, 1}]}, + MonTime = erlang:monotonic_time(), + TimeOffset = erlang:time_offset(), + Fixed = {{MonTime, TimeOffset}, [{Pid, 1}]}, Ftab = dets_utils:get_freelists(Head), Head#head{fixed = Fixed, freelists = {Ftab, Ftab}}; {TimeStamp, Counters} -> @@ -2091,7 +2093,22 @@ finfo(H, no_keys) -> finfo(H, no_slots) -> {H, (H#head.mod):no_slots(H)}; finfo(H, pid) -> {H, self()}; finfo(H, ram_file) -> {H, H#head.ram_file}; -finfo(H, safe_fixed) -> {H, H#head.fixed}; +finfo(H, safe_fixed) -> + {H, + case H#head.fixed of + false -> + false; + {{FixMonTime, TimeOffset}, RefList} -> + {make_timestamp(FixMonTime, TimeOffset), RefList} + end}; +finfo(H, safe_fixed_monotonic_time) -> + {H, + case H#head.fixed of + false -> + false; + {{FixMonTime, _TimeOffset}, RefList} -> + {FixMonTime, RefList} + end}; finfo(H, size) -> case catch write_cache(H) of {H2, []} -> @@ -3275,11 +3292,14 @@ err(Error) -> time_now() -> erlang:monotonic_time(1000000). --compile({inline, [utime_now/0]}). -utime_now() -> - Time = time_now(), - UniqueCounter = erlang:unique_integer([monotonic]), - {Time, UniqueCounter}. +make_timestamp(MonTime, TimeOffset) -> + ErlangSystemTime = erlang:convert_time_unit(MonTime+TimeOffset, + native, + micro_seconds), + MegaSecs = ErlangSystemTime div 1000000000000, + Secs = ErlangSystemTime div 1000000 - MegaSecs*1000000, + MicroSecs = ErlangSystemTime rem 1000000, + {MegaSecs, Secs, MicroSecs}. %%%%%%%%%%%%%%%%% DEBUG functions %%%%%%%%%%%%%%%% diff --git a/lib/stdlib/src/ets.erl b/lib/stdlib/src/ets.erl index 847def2fd8..1fca3624dc 100644 --- a/lib/stdlib/src/ets.erl +++ b/lib/stdlib/src/ets.erl @@ -146,7 +146,7 @@ info(_) -> Tab :: tab(), Item :: compressed | fixed | heir | keypos | memory | name | named_table | node | owner | protection - | safe_fixed | size | stats | type + | safe_fixed | safe_fixed_monotonic_time | size | stats | type | write_concurrency | read_concurrency, Value :: term(). diff --git a/lib/stdlib/src/stdlib.app.src b/lib/stdlib/src/stdlib.app.src index 7f9bbbf649..b8a7973cf2 100644 --- a/lib/stdlib/src/stdlib.app.src +++ b/lib/stdlib/src/stdlib.app.src @@ -105,7 +105,7 @@ dets]}, {applications, [kernel]}, {env, []}, - {runtime_dependencies, ["sasl-2.6","kernel-4.1","erts-7.0","crypto-3.3", + {runtime_dependencies, ["sasl-2.6","kernel-4.1","erts-7.3","crypto-3.3", "compiler-5.0"]} ]}. diff --git a/lib/stdlib/test/dets_SUITE.erl b/lib/stdlib/test/dets_SUITE.erl index 7f5e06524a..35e587afcc 100644 --- a/lib/stdlib/test/dets_SUITE.erl +++ b/lib/stdlib/test/dets_SUITE.erl @@ -1876,9 +1876,33 @@ fixtable(Config, Version) when is_list(Config) -> {ok, _} = dets:open_file(T, [{type, duplicate_bag} | Args]), %% In a fixed table, delete and re-insert an object. ok = dets:insert(T, {1, a, b}), + SysBefore = erlang:timestamp(), + MonBefore = erlang:monotonic_time(), dets:safe_fixtable(T, true), + MonAfter = erlang:monotonic_time(), + SysAfter = erlang:timestamp(), + Self = self(), + {FixMonTime,[{Self,1}]} = dets:info(T,safe_fixed_monotonic_time), + {FixSysTime,[{Self,1}]} = dets:info(T,safe_fixed), + true = is_integer(FixMonTime), + true = MonBefore =< FixMonTime, + true = FixMonTime =< MonAfter, + {FstMs,FstS,FstUs} = FixSysTime, + true = is_integer(FstMs), + true = is_integer(FstS), + true = is_integer(FstUs), + case erlang:system_info(time_warp_mode) of + no_time_warp -> + true = timer:now_diff(FixSysTime, SysBefore) >= 0, + true = timer:now_diff(SysAfter, FixSysTime) >= 0; + _ -> + %% ets:info(Tab,safe_fixed) not timewarp safe... + ignore + end, ok = dets:match_delete(T, {1, a, b}), ok = dets:insert(T, {1, a, b}), + {FixMonTime,[{Self,1}]} = dets:info(T,safe_fixed_monotonic_time), + {FixSysTime,[{Self,1}]} = dets:info(T,safe_fixed), dets:safe_fixtable(T, false), 1 = length(dets:match_object(T, '_')), diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl index ae431d66d9..30a158d9e1 100644 --- a/lib/stdlib/test/ets_SUITE.erl +++ b/lib/stdlib/test/ets_SUITE.erl @@ -3989,15 +3989,37 @@ safe_fixtable_do(Opts) -> ?line true = ets:safe_fixtable(Tab, true), ?line receive after 1 -> ok end, ?line true = ets:safe_fixtable(Tab, false), - ?line false = ets:info(Tab,safe_fixed), - ?line true = ets:safe_fixtable(Tab, true), + false = ets:info(Tab,safe_fixed_monotonic_time), + false = ets:info(Tab,safe_fixed), + SysBefore = erlang:timestamp(), + MonBefore = erlang:monotonic_time(), + true = ets:safe_fixtable(Tab, true), + MonAfter = erlang:monotonic_time(), + SysAfter = erlang:timestamp(), Self = self(), - ?line {{_,_,_},[{Self,1}]} = ets:info(Tab,safe_fixed), + {FixMonTime,[{Self,1}]} = ets:info(Tab,safe_fixed_monotonic_time), + {FixSysTime,[{Self,1}]} = ets:info(Tab,safe_fixed), + true = is_integer(FixMonTime), + true = MonBefore =< FixMonTime, + true = FixMonTime =< MonAfter, + {FstMs,FstS,FstUs} = FixSysTime, + true = is_integer(FstMs), + true = is_integer(FstS), + true = is_integer(FstUs), + case erlang:system_info(time_warp_mode) of + no_time_warp -> + true = timer:now_diff(FixSysTime, SysBefore) >= 0, + true = timer:now_diff(SysAfter, FixSysTime) >= 0; + _ -> + %% ets:info(Tab,safe_fixed) not timewarp safe... + ignore + end, %% Test that an unjustified 'unfix' is a no-op. {Pid,MRef} = my_spawn_monitor(fun() -> true = ets:safe_fixtable(Tab,false) end), {'DOWN', MRef, process, Pid, normal} = receive M -> M end, - ?line true = ets:info(Tab,fixed), - ?line {{_,_,_},[{Self,1}]} = ets:info(Tab,safe_fixed), + true = ets:info(Tab,fixed), + {FixMonTime,[{Self,1}]} = ets:info(Tab,safe_fixed_monotonic_time), + {FixSysTime,[{Self,1}]} = ets:info(Tab,safe_fixed), %% badarg's ?line {'EXIT', {badarg, _}} = (catch ets:safe_fixtable(Tab, foobar)), ?line true = ets:info(Tab,fixed), @@ -4043,6 +4065,7 @@ info_do(Opts) -> ?line undefined = ets:info(non_existing_table_xxyy,type), ?line undefined = ets:info(non_existing_table_xxyy,node), ?line undefined = ets:info(non_existing_table_xxyy,named_table), + ?line undefined = ets:info(non_existing_table_xxyy,safe_fixed_monotonic_time), ?line undefined = ets:info(non_existing_table_xxyy,safe_fixed), ?line verify_etsmem(EtsMem). @@ -5532,7 +5555,7 @@ otp_8166_zombie_creator(T,Deleted) -> [{'=<','$1', Deleted}], [true]}]), Pid ! zombies_created, - repeat_while(fun() -> case ets:info(T,safe_fixed) of + repeat_while(fun() -> case ets:info(T,safe_fixed_monotonic_time) of {_,[_P1,_P2]} -> false; _ -> |