Merge branch 'mdsteele-threadid'

5 files changed, 72 insertions, 7 deletions

diff --git a/std/c/index.zig b/std/c/index.zig
index 7de8634d07..738b2f9c05 100644
--- a/std/c/index.zig
+++ b/std/c/index.zig
@@ -58,6 +58,7 @@ pub extern "pthread" fn pthread_create(noalias newthread: *pthread_t, noalias at
 pub extern "pthread" fn pthread_attr_init(attr: *pthread_attr_t) c_int;
 pub extern "pthread" fn pthread_attr_setstack(attr: *pthread_attr_t, stackaddr: *c_void, stacksize: usize) c_int;
 pub extern "pthread" fn pthread_attr_destroy(attr: *pthread_attr_t) c_int;
+pub extern "pthread" fn pthread_self() pthread_t;
 pub extern "pthread" fn pthread_join(thread: pthread_t, arg_return: ?*?*c_void) c_int;
 
 pub const pthread_t = *@OpaqueType();
diff --git a/std/os/index.zig b/std/os/index.zig
index 425a900a71..d47444d67d 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -160,7 +160,7 @@ test "os.getRandomBytes" {
     try getRandomBytes(buf_b[0..]);
 
     // Check if random (not 100% conclusive)
-    assert( !mem.eql(u8, buf_a, buf_b) );
+    assert(!mem.eql(u8, buf_a, buf_b));
 }
 
 /// Raises a signal in the current kernel thread, ending its execution.
@@ -2516,26 +2516,66 @@ pub const Thread = struct {
     data: Data,
 
     pub const use_pthreads = is_posix and builtin.link_libc;
+
+    /// Represents a kernel thread handle.
+    /// May be an integer or a pointer depending on the platform.
+    /// On Linux and POSIX, this is the same as Id.
+    pub const Handle = if (use_pthreads)
+        c.pthread_t
+    else switch (builtin.os) {
+        builtin.Os.linux => i32,
+        builtin.Os.windows => windows.HANDLE,
+        else => @compileError("Unsupported OS"),
+    };
+
+    /// Represents a unique ID per thread.
+    /// May be an integer or pointer depending on the platform.
+    /// On Linux and POSIX, this is the same as Handle.
+    pub const Id = switch (builtin.os) {
+        builtin.Os.windows => windows.DWORD,
+        else => Handle,
+    };
+
     pub const Data = if (use_pthreads)
         struct {
-            handle: c.pthread_t,
+            handle: Thread.Handle,
             stack_addr: usize,
             stack_len: usize,
         }
     else switch (builtin.os) {
         builtin.Os.linux => struct {
-            pid: i32,
+            handle: Thread.Handle,
             stack_addr: usize,
             stack_len: usize,
         },
         builtin.Os.windows => struct {
-            handle: windows.HANDLE,
+            handle: Thread.Handle,
             alloc_start: *c_void,
             heap_handle: windows.HANDLE,
         },
         else => @compileError("Unsupported OS"),
     };
 
+    /// Returns the ID of the calling thread.
+    /// Makes a syscall every time the function is called.
+    /// On Linux and POSIX, this Id is the same as a Handle.
+    pub fn getCurrentId() Id {
+        if (use_pthreads) {
+            return c.pthread_self();
+        } else
+            return switch (builtin.os) {
+            builtin.Os.linux => linux.gettid(),
+            builtin.Os.windows => windows.GetCurrentThreadId(),
+            else => @compileError("Unsupported OS"),
+        };
+    }
+
+    /// Returns the handle of this thread.
+    /// On Linux and POSIX, this is the same as Id.
+    pub fn handle(self: Thread) Handle {
+        return self.data.handle;
+    }
+
     pub fn wait(self: *const Thread) void {
         if (use_pthreads) {
             const err = c.pthread_join(self.data.handle, null);
@@ -2550,9 +2590,9 @@ pub const Thread = struct {
         } else switch (builtin.os) {
             builtin.Os.linux => {
                 while (true) {
-                    const pid_value = @atomicLoad(i32, &self.data.pid, builtin.AtomicOrder.SeqCst);
+                    const pid_value = @atomicLoad(i32, &self.data.handle, builtin.AtomicOrder.SeqCst);
                     if (pid_value == 0) break;
-                    const rc = linux.futex_wait(@ptrToInt(&self.data.pid), linux.FUTEX_WAIT, pid_value, null);
+                    const rc = linux.futex_wait(@ptrToInt(&self.data.handle), linux.FUTEX_WAIT, pid_value, null);
                     switch (linux.getErrno(rc)) {
                         0 => continue,
                         posix.EINTR => continue,
@@ -2734,7 +2774,7 @@ pub fn spawnThread(context: var, comptime startFn: var) SpawnThreadError!*Thread
         // use linux API directly.  TODO use posix.CLONE_SETTLS and initialize thread local storage correctly
         const flags = posix.CLONE_VM | posix.CLONE_FS | posix.CLONE_FILES | posix.CLONE_SIGHAND | posix.CLONE_THREAD | posix.CLONE_SYSVSEM | posix.CLONE_PARENT_SETTID | posix.CLONE_CHILD_CLEARTID | posix.CLONE_DETACHED;
         const newtls: usize = 0;
-        const rc = posix.clone(MainFuncs.linuxThreadMain, stack_end, flags, arg, &thread_ptr.data.pid, newtls, &thread_ptr.data.pid);
+        const rc = posix.clone(MainFuncs.linuxThreadMain, stack_end, flags, arg, &thread_ptr.data.handle, newtls, &thread_ptr.data.handle);
         const err = posix.getErrno(rc);
         switch (err) {
             0 => return thread_ptr,
diff --git a/std/os/linux/index.zig b/std/os/linux/index.zig
index 15607ea6c0..15ca649f06 100644
--- a/std/os/linux/index.zig
+++ b/std/os/linux/index.zig
@@ -947,6 +947,10 @@ pub fn getpid() i32 {
     return @bitCast(i32, @truncate(u32, syscall0(SYS_getpid)));
 }
 
+pub fn gettid() i32 {
+    return @bitCast(i32, @truncate(u32, syscall0(SYS_gettid)));
+}
+
 pub fn sigprocmask(flags: u32, noalias set: *const sigset_t, noalias oldset: ?*sigset_t) usize {
     return syscall4(SYS_rt_sigprocmask, flags, @ptrToInt(set), @ptrToInt(oldset), NSIG / 8);
 }
diff --git a/std/os/test.zig b/std/os/test.zig
index 9e795e8ad2..82054d3f32 100644
--- a/std/os/test.zig
+++ b/std/os/test.zig
@@ -34,6 +34,23 @@ test "access file" {
     try os.deleteTree(a, "os_test_tmp");
 }
 
+fn testThreadIdFn(thread_id: *os.Thread.Id) void {
+    thread_id.* = os.Thread.getCurrentId();
+}
+
+test "std.os.Thread.getCurrentId" {
+    var thread_current_id: os.Thread.Id = undefined;
+    const thread = try os.spawnThread(&thread_current_id, testThreadIdFn);
+    const thread_id = thread.handle();
+    thread.wait();
+    switch (builtin.os) {
+        builtin.Os.windows => assert(os.Thread.getCurrentId() != thread_current_id),
+        else => {
+            assert(thread_current_id == thread_id);
+        },
+    }
+}
+
 test "spawn threads" {
     var shared_ctx: i32 = 1;
 
diff --git a/std/os/windows/kernel32.zig b/std/os/windows/kernel32.zig
index fa3473ad05..daeebf1021 100644
--- a/std/os/windows/kernel32.zig
+++ b/std/os/windows/kernel32.zig
@@ -63,6 +63,9 @@ pub extern "kernel32" stdcallcc fn GetConsoleMode(in_hConsoleHandle: HANDLE, out
 
 pub extern "kernel32" stdcallcc fn GetCurrentDirectoryA(nBufferLength: WORD, lpBuffer: ?LPSTR) DWORD;
 
+pub extern "kernel32" stdcallcc fn GetCurrentThread() HANDLE;
+pub extern "kernel32" stdcallcc fn GetCurrentThreadId() DWORD;
+
 pub extern "kernel32" stdcallcc fn GetEnvironmentStringsA() ?[*]u8;
 
 pub extern "kernel32" stdcallcc fn GetEnvironmentVariableA(lpName: LPCSTR, lpBuffer: LPSTR, nSize: DWORD) DWORD;