Electrolysis/Logging: Difference between revisions

Revision as of 22:10, 13 May 2016

need to sort out current state of MOZ logging and other forms of IPC related logging
Sandboxing. Approaches to writing logs from sandboxed child processes include:
- Open files early, either during startup or from a sandboxing-specific hook, rather than opening lazily on first use. Not ideal for log files that might not be used at all.
- Have the parent open file descriptors and send them to the child; see PCycleCollectWithLogs for one example. Works well with code using stdio or NSPR, and less well with C++ iostreams.
- Send the data in chunks over IPC messages (e.g., using bug 1093357 once that lands); note that Gecko IPC has no flow control, so OOM is a possibility if the receiver can't keep up. Also problematic if logging is to be done from multiple threads.
Logging.h
bug 881389 (OneLogger) Improve Gecko's logging story

bug 1272704 NSPR logging appears to be broken on Windows from Content processes
bug 1014407 Failure when setting stdout or stderr on the Windows process sandboxing policy should be reported as a warning
bug 1055227 Make sandbox logging (security/sandbox/chromium/base/shim/base/logging*) actually emit log messsages
bug 1198475 Mochitest log file opened directly in content process

@@ Line 2: / Line 2: @@
 * need to sort out current state of MOZ logging and other forms of IPC related logging
-* How does sandboxing impact this
+* Sandboxing.  Approaches to writing logs from sandboxed child processes include:
+** Open files early, either during startup or from a sandboxing-specific hook, rather than opening lazily on first use.  Not ideal for log files that might not be used at all.
+** Have the parent open file descriptors and send them to the child; see [https://dxr.mozilla.org/mozilla-central/search?q=PCycleCollectWithLogs <tt>PCycleCollectWithLogs</tt>] for one example.  Works well with code using <tt>stdio</tt> or NSPR, and less well with C++ iostreams.
+** Send the data in chunks over IPC messages (e.g., using {{bug|1093357}} once that lands); note that Gecko IPC has no flow control, so OOM is a possibility if the receiver can't keep up.  Also problematic if logging is to be done from multiple threads.
 * [http://mxr.mozilla.org/mozilla-central/source/xpcom/base/Logging.h Logging.h]
 * {{bug|881389}} (OneLogger) Improve Gecko's logging story