Trying again to land OOM priority manager changes.

base/process_util.h

Index: base/process_util.h
diff --git a/base/process_util.h b/base/process_util.h
index b98e266a97870d7231279b6cc91c9194dfa60638..2109401e1807b55ad60caa0300bad00e94787f04 100644
--- a/base/process_util.h
+++ b/base/process_util.h
@@ -173,13 +173,18 @@ BASE_EXPORT FilePath GetProcessExecutablePath(ProcessHandle process);
 // Exposed for testing.
 BASE_EXPORT int ParseProcStatCPU(const std::string& input);
 
-static const char kAdjustOOMScoreSwitch[] = "--adjust-oom-score";

[Greg Spencer (Chromium), 2011/08/22 23:28:48]

First landing failed because of an obscure problem with building
linux_shared.  This new change is identical to the original, with the
exception that I reverted this minor change that moved a static const
char[] out of process_util.h in base/ (where it should not be, IMO)
and into the .cc file.  Unfortunately, that causes the linux_shared
build to fail for a reason that is still not clear to me, as libbase
is linked into all the executables which failed to link because they
thought this symbol was missing.  They only failed to link in the
linux_shared build, so it certainly has something to do with our
shared library build.

Instead of leaving the static string in process_util.h, I moved it to
be closer to the one call site that used it, since I don't think that
a switch that is used only by the suid sandbox and its callers on
Linux belongs in base/, especially when there is only one use of the
string, and especially not as a static that gets defined in every
compilation unit that includes it. The suid sandbox doesn't include
anything from base, so we can't re-use the string there.

-
-// This adjusts /proc/process/oom_adj so the Linux OOM killer will prefer
-// certain process types over others. The range for the adjustment is
-// [-17,15], with [0,15] being user accessible.
+// The maximum allowed value for the OOM score.
+const int kMaxOomScore = 1000;
+
+// This adjusts /proc/<pid>/oom_score_adj so the Linux OOM killer will
+// prefer to kill certain process types over others. The range for the
+// adjustment is [-1000, 1000], with [0, 1000] being user accessible.
+// If the Linux system doesn't support the newer oom_score_adj range
+// of [0, 1000], then we revert to using the older oom_adj, and
+// translate the given value into [0, 15].  Some aliasing of values
+// may occur in that case, of course.
 BASE_EXPORT bool AdjustOOMScore(ProcessId process, int score);
-#endif
+#endif  // defined(OS_LINUX)
 
 #if defined(OS_POSIX)
 // Returns the ID for the parent of the given process.
@@ -189,7 +194,7 @@ BASE_EXPORT ProcessId GetParentProcessId(ProcessHandle process);
 // given multimap. Only call this function in a child process where you know
 // that there aren't any other threads.
 BASE_EXPORT void CloseSuperfluousFds(const InjectiveMultimap& saved_map);
-#endif
+#endif  // defined(OS_POSIX)
 
 // TODO(evan): rename these to use StudlyCaps.
 typedef std::vector<std::pair<std::string, std::string> > environment_vector;
@@ -205,7 +210,7 @@ struct LaunchOptions {
 #else
                     environ(NULL), fds_to_remap(NULL), new_process_group(false),
                     clone_flags(0)
-#endif
+#endif  // !defined(OS_WIN)
       {}
 
   // If true, wait for the process to complete.
@@ -248,7 +253,7 @@ struct LaunchOptions {
 
   // If non-zero, start the process using clone(), using flags as provided.
   int clone_flags;
-#endif
+#endif   // !defined(OS_WIN)
 };
 
 // Launch a process via the command line |cmdline|.
@@ -335,7 +340,7 @@ BASE_EXPORT bool GetAppOutputRestricted(const CommandLine& cl,
 // |*exit_code|.
 BASE_EXPORT bool GetAppOutputWithExitCode(const CommandLine& cl,
                                           std::string* output, int* exit_code);
-#endif
+#endif  // defined(OS_POSIX)
 
 // Used to filter processes by process ID.
 class ProcessFilter {
@@ -372,12 +377,12 @@ BASE_EXPORT bool KillProcess(ProcessHandle process, int exit_code, bool wait);
 // Attempts to kill the process group identified by |process_group_id|. Returns
 // true on success.
 BASE_EXPORT bool KillProcessGroup(ProcessHandle process_group_id);
-#endif
+#endif  // defined(OS_POSIX)
 
 #if defined(OS_WIN)
 BASE_EXPORT bool KillProcessById(ProcessId process_id, int exit_code,
                                  bool wait);
-#endif
+#endif  // defined(OS_WIN)
 
 // Get the termination status of the process by interpreting the
 // circumstances of the child process' death. |exit_code| is set to
@@ -632,7 +637,7 @@ class BASE_EXPORT ProcessMetrics {
   explicit ProcessMetrics(ProcessHandle process);
 #else
   ProcessMetrics(ProcessHandle process, PortProvider* port_provider);
-#endif  // !defined(OS_MACOSX)
+#endif  // defined(OS_MACOSX)
 
   ProcessHandle process_;
 
@@ -651,7 +656,7 @@ class BASE_EXPORT ProcessMetrics {
 #elif defined(OS_POSIX)
   // Jiffie count at the last_time_ we updated.
   int last_cpu_;
-#endif  // defined(OS_MACOSX)
+#endif  // defined(OS_POSIX)
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMetrics);
 };
@@ -674,7 +679,7 @@ struct SystemMemoryInfoKB {
 // Fills in the provided |meminfo| structure. Returns true on success.
 // Exposed for memory debugging widget.
 BASE_EXPORT bool GetSystemMemoryInfo(SystemMemoryInfoKB* meminfo);
-#endif
+#endif  // defined(OS_LINUX)
 
 // Returns the memory committed by the system in KBytes.
 // Returns 0 if it can't compute the commit charge.
@@ -699,8 +704,8 @@ BASE_EXPORT void EnableTerminationOnOutOfMemory();
 #if defined(OS_MACOSX)
 // Exposed for testing.
 BASE_EXPORT malloc_zone_t* GetPurgeableZone();
-#endif
-#endif
+#endif  // defined(OS_MACOSX)
+#endif  // !defined(OS_WIN)
 
 // Enables stack dump to console output on exception and signals.
 // When enabled, the process will quit immediately. This is meant to be used in