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authorRickard Green <[email protected]>2016-01-13 18:33:42 +0100
committerRickard Green <[email protected]>2016-01-20 11:10:37 +0100
commitdc8e62f33ad0ca7a772ec74d67b6d3e157f639b4 (patch)
treedfb9c44328ba358c34678d557941a13b79e3d281 /lib/stdlib
parent858c6f7fa44f7b2dc363b359198d6522dd60e914 (diff)
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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.xml31
-rw-r--r--lib/stdlib/doc/src/ets.xml41
-rw-r--r--lib/stdlib/src/dets.erl36
-rw-r--r--lib/stdlib/src/ets.erl2
-rw-r--r--lib/stdlib/src/stdlib.app.src2
-rw-r--r--lib/stdlib/test/dets_SUITE.erl24
-rw-r--r--lib/stdlib/test/ets_SUITE.erl35
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;
_ ->