process: replace crucible::gettid() with a weak symbol

Since we're now using weak symbols for dodgy libc functions, we might
as well do it for gettid() too.

Use the ::gettid() global namespace and let libc override it.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

include/crucible/lockset.h

@@ -117,7 +117,7 @@ namespace crucible {
 		while (full() || locked(name)) {
 			m_condvar.wait(lock);
 		}
-		auto rv = m_set.insert(make_pair(name, crucible::gettid()));
+		auto rv = m_set.insert(make_pair(name, gettid()));
 		THROW_CHECK0(runtime_error, rv.second);
 	}
 
@@ -129,7 +129,7 @@ namespace crucible {
 		if (full() || locked(name)) {
 			return false;
 		}
-		auto rv = m_set.insert(make_pair(name, crucible::gettid()));
+		auto rv = m_set.insert(make_pair(name, gettid()));
 		THROW_CHECK1(runtime_error, name, rv.second);
 		return true;
 	}

include/crucible/process.h

@@ -10,6 +10,10 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+extern "C" {
+	pid_t gettid() throw();
+};
+
 namespace crucible {
 	using namespace std;
 
@@ -73,7 +77,6 @@ namespace crucible {
 
 	typedef ResourceHandle<Process::id, Process> Pid;
 
-	pid_t gettid();
 	double getloadavg1();
 	double getloadavg5();
 	double getloadavg15();

lib/chatter.cc

@@ -76,7 +76,7 @@ namespace crucible {
 			DIE_IF_ZERO(strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", &ltm));
 
 			header_stream << buf;
-			header_stream << " " << getpid() << "." << crucible::gettid();
+			header_stream << " " << getpid() << "." << gettid();
 			if (add_prefix_level) {
 				header_stream << "<" << m_loglevel << ">";
 			}
@@ -88,7 +88,7 @@ namespace crucible {
 				header_stream << "<" << m_loglevel << ">";
 			}
 			header_stream << (m_name.empty() ? "thread" : m_name);
-			header_stream << "[" << crucible::gettid() << "]";
+			header_stream << "[" << gettid() << "]";
 		}
 
 		header_stream << ": ";

lib/process.cc

@@ -7,13 +7,18 @@
 #include <cstdlib>
 #include <utility>
 
-// for gettid()
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
 #include <unistd.h>
 #include <sys/syscall.h>
 
+extern "C" {
+	pid_t
+	__attribute__((weak))
+	gettid() throw()
+	{
+		return syscall(SYS_gettid);
+	}
+};
+
 namespace crucible {
 	using namespace std;
 
@@ -111,12 +116,6 @@ namespace crucible {
 		}
 	}
 
-	pid_t
-	gettid()
-	{
-		return syscall(SYS_gettid);
-	}
-
 	double
 	getloadavg1()
 	{

src/bees-trace.cc

@@ -91,9 +91,9 @@ BeesNote::~BeesNote()
 	tl_next = m_prev;
 	unique_lock<mutex> lock(s_mutex);
 	if (tl_next) {
-		s_status[crucible::gettid()] = tl_next;
+		s_status[gettid()] = tl_next;
 	} else {
-		s_status.erase(crucible::gettid());
+		s_status.erase(gettid());
 	}
 }
 
@@ -104,7 +104,7 @@ BeesNote::BeesNote(function<void(ostream &os)> f) :
 	m_prev = tl_next;
 	tl_next = this;
 	unique_lock<mutex> lock(s_mutex);
-	s_status[crucible::gettid()] = tl_next;
+	s_status[gettid()] = tl_next;
 }
 
 void