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The read lock checks for the G_DATABASES rwlock were incorrect. Multiple readers

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are possible.  Now the check for exclusive port/thread is only done on writes.

Added an integration test that reproduces conditions seen during the local-storage-ops-
in-coord branch.
This commit is contained in:
Jon Meredith 2009-06-19 08:44:43 -06:00 committed by Phillip Toland
parent 3d422bec1d
commit 7c9da71b18
2 changed files with 72 additions and 8 deletions
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18
c_src/bdberl_drv.c
View file

@ -139,8 +139,8 @@ static Database* G_DATABASES = 0;
static Database* G_DATABASES_SHADOW = 0;
static unsigned int G_DATABASES_SIZE = 0;
static ErlDrvRWLock* G_DATABASES_RWLOCK = 0;
static volatile ErlDrvTid G_DATABASES_RWLOCK_TID = 0;
static volatile ErlDrvPort G_DATABASES_RWLOCK_PORT = 0;
static volatile ErlDrvTid G_DATABASES_RWLOCK_TID = 0; /* TID for writers */
static volatile ErlDrvPort G_DATABASES_RWLOCK_PORT = 0; /* Port for writers */
static hive_hash* G_DATABASES_NAMES = 0;
@ -220,26 +220,26 @@ static void DBGCMDRC(PortData *d, int rc);
void READ_LOCK_DATABASES(void *x, ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: read locking G_DATABASES\r\n", self, P);
erl_drv_rwlock_rlock(G_DATABASES_RWLOCK);
assert(0 == G_DATABASES_RWLOCK_TID);
assert(0 == G_DATABASES_RWLOCK_PORT);
G_DATABASES_RWLOCK_TID = self;
G_DATABASES_RWLOCK_PORT = P;
assert(0 == memcmp(G_DATABASES, G_DATABASES_SHADOW, sizeof(G_DATABASES[0])*G_DATABASES_SIZE));
DBG("threadid %p port %p: read locked G_DATABASES\r\n", self, P);
}
void READ_UNLOCK_DATABASES(void *x, ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: read unlocking G_DATABASES\r\n", self, P);
assert(erl_drv_thread_self() == G_DATABASES_RWLOCK_TID);
assert(P == G_DATABASES_RWLOCK_PORT);
assert(0 == G_DATABASES_RWLOCK_TID);
assert(0 == G_DATABASES_RWLOCK_PORT);
assert(0 == memcmp(G_DATABASES, G_DATABASES_SHADOW, sizeof(G_DATABASES[0])*G_DATABASES_SIZE));
G_DATABASES_RWLOCK_TID = 0;
G_DATABASES_RWLOCK_PORT = 0;
erl_drv_rwlock_runlock(G_DATABASES_RWLOCK);
DBG("threadid %p port %p: read unlocked G_DATABASES\r\n", self, P);
}
@ -263,7 +263,9 @@ void WRITE_LOCK_DATABASES(void *x, ErlDrvPort P)
void WRITE_UNLOCK_DATABASES(void *x, ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: write unlocking G_DATABASES\r\n", self, P);
assert(erl_drv_thread_self() == G_DATABASES_RWLOCK_TID);
assert(P == G_DATABASES_RWLOCK_PORT);

62
int_test/bug200_SUITE.erl Normal file
View file

@ -0,0 +1,62 @@
%% -------------------------------------------------------------------
%%
%% bdberl: Port Driver Bug200 tests
%% Copyright (c) 2008 The Hive. All rights reserved.
%%
%% -------------------------------------------------------------------
-module(bug200_SUITE).
-compile(export_all).
-define(PROCS, 32).
all() ->
[bug200].
bug200(_Config) ->
%% Spin up 15 processes (async thread pool is 10)
start_procs(?PROCS),
wait_for_finish(?PROCS).
start_procs(0) ->
ok;
start_procs(Count) ->
spawn_link(?MODULE, bug200_run, [self()]),
start_procs(Count-1).
wait_for_finish(0) ->
ok;
wait_for_finish(Count) ->
receive
{finished, Pid} ->
ct:print("~p is done; ~p remaining.\n", [Pid, Count-1]),
wait_for_finish(Count-1)
end.
bug200_run(Owner) ->
%% Seed the RNG
{A1, A2, A3} = now(),
random:seed(A1, A2, A3),
%% Start bug200ing
bug200_incr_loop(Owner, 1000).
bug200_incr_loop(Owner, 0) ->
Owner ! {finished, self()};
bug200_incr_loop(Owner, Count) ->
% ct:print("~p", [Count]),
%% Choose random key
Key = random:uniform(1200),
File = "bug200_" ++ integer_to_list(random:uniform(16)) ++ ".bdb",
%% Start a txn that will read the current value of the key and increment by 1
F = fun(_Key, Value) ->
case Value of
not_found -> 0;
Value -> Value + 1
end
end,
%% Open up a port and database
{ok, DbRef} = bdberl:open(File, btree),
{ok, _} = bdberl:update(DbRef, Key, F),
ok = bdberl:close(DbRef),
bug200_incr_loop(Owner, Count-1).