23694 - Enable the NT native-threads-only mode by a global variable

Status: RESOLVED FIXED

(NSPR :: NSPR, enhancement, P3)

Description

[Wan-Teh Chang]

Right now one enables the NT native-threads-only mode by
setting the environment variable NSPR_NATIVE_THREADS_ONLY
to 1.  Although each process has its own environment,
all NT services inherit the *system* environment. This
means the NT services using NSPR cannot have different
settings of the native-threads-only mode.

It is proposed that we add a new way to enable the
native-threads-only mode that allows individual NT
services to have different settings.  We can achieve this
by having the main executable defining a DLL-exported
global variable, and having NSPR look up that global
variable during initialization.

Suppose the global variable is named nspr_native_threads_only.
A server that wants to enable the native-threads-only mode
would define this variable in a file that is part of the main
executable program as follows:

#ifdef WINNT
/* enable NSPR native-threads-only mode */
PR_IMPLEMENT_DATA(PRBool) nspr_native_threads_only = PR_TRUE;
#endif

I suggest that this new method have precedence over the old environment
variable method.  That is, if the nspr_native_threads_only
global variable is defined, NSPR ignores the NSPR_NATIVE_THREADS_ONLY
environment variable.

Comment 1

[Wan-Teh Chang]

Attachment: Proposed patch.

Comment 2

[Wan-Teh Chang]

Some comments on the proposed patch:
1. The magic global variable "nspr_native_threads_only"
   is of the type PRBool.  It must be defined in the main
   executable using the DLL-export qualifier (e.g., the
   PR_IMPLEMENT_DATA macro).
2. The magic global variable has precedence over the
   magic environment variable.

Comment 3

[srinivas]

The patch looks good. It can be made more general to allow setting or resetting
of the native-threads-only mode when nspr_native_threads_only is PR_TRUE and
PR_FALSE respectively, independent of the default mode. Same applies for the
environment variable.

Comment 4

[Wan-Teh Chang]

Attachment: Revised patch to allow setting and unsetting of the mode, independent of the default.

Comment 5

[srinivas]

Patch looks good.

Comment 6

[Wan-Teh Chang]

The fix is checked in.
/cvsroot/mozilla/nsprpub/pr/src/misc/prinit.c, revision 3.18

The fix is also checked into the internal repository.
/m/src/ns/nspr20/pr/src/misc/prinit.c, revision 2.38

Comment 7

[Pulsebot]

Pushed by ffxbld-merge:
https://hg.mozilla.org/releases/mozilla-beta/rev/1a33283c7f3f
[fenix] Close https://github.com/mozilla-mobile/fenix/issues/23694: Add telemetry for history search