builtin: add pid: and tid: fields to the panic reports (part 2 of #25808) (#25809)

Author: spytheman

vlib/builtin/builtin.c.v

@@ -64,16 +64,21 @@ fn panic_debug(line_no int, file string, mod string, fn_name string, s string) {
 	} $else {
 		// vfmt off
 		// Note: be carefull to not allocate here, avoid string interpolation
+		flush_stdout()
 		eprintln('================ V panic ================')
 		eprint('   module: '); eprintln(mod)
 		eprint(' function: '); eprint(fn_name); eprintln('()')
 		eprint('  message: '); eprintln(s)
 		eprint('     file: '); eprint(file); eprint(':');
-		C.fprintf(C.stderr, c'%d\n', line_no)
+	    C.fprintf(C.stderr, c'%d\n', line_no)
 		eprint('   v hash: '); eprintln(vcurrent_hash())
+		$if !vinix && !native {
+			eprint('      pid: '); C.fprintf(C.stderr, c'%p\n', voidptr(v_getpid()))
+			eprint('      tid: '); C.fprintf(C.stderr, c'%p\n', voidptr(v_gettid()))
+		}
 		eprintln('=========================================')
-		// vfmt on
 		flush_stdout()
+		// vfmt on
 		$if native {
 			C.exit(1) // TODO: native backtraces
 		} $else $if exit_after_panic_message ? {
@@ -129,11 +134,18 @@ pub fn panic(s string) {
 	$if freestanding {
 		bare_panic(s)
 	} $else {
+		// vfmt off
+		flush_stdout()
 		eprint('V panic: ')
 		eprintln(s)
-		eprint('v hash: ')
+		eprint(' v hash: ')
 		eprintln(vcurrent_hash())
+		$if !vinix && !native {
+			eprint('    pid: '); C.fprintf(C.stderr, c'%p\n', voidptr(v_getpid()))
+			eprint('    tid: '); C.fprintf(C.stderr, c'%p\n', voidptr(v_gettid()))
+		}
 		flush_stdout()
+		// vfmt on
 		$if native {
 			C.exit(1) // TODO: native backtraces
 		} $else $if exit_after_panic_message ? {
@@ -948,3 +960,34 @@ pub fn arguments() []string {
 	}
 	return res
 }
+
+// v_getpid returns a process identifier. It is a number that is guaranteed to
+// remain the same while the current process is running. It may or may not be
+// equal to the value of v_gettid(). Note: it is *NOT equal on Windows*.
+pub fn v_getpid() u64 {
+	$if windows {
+		return u64(C.GetCurrentProcessId())
+	} $else {
+		return u64(C.getpid())
+	}
+}
+
+// v_gettid retuns a thread identifier. It is a number that is guaranteed to not
+// change, while the current thread is running. Different threads, running at
+// the same time in the same process, have different thread ids. There is no
+// such guarantee for threads running in different processes.
+// Important: this will be the same number returned by v_getpid(), but only on
+// non windows systems, when the current thread is the main one. It is best to
+// *avoid relying on this equivalence*, and use v_gettid and v_getpid only for
+// tracing and debugging multithreaded issues, but *NOT for logic decisions*.
+pub fn v_gettid() u64 {
+	$if windows {
+		return u64(C.GetCurrentThreadId())
+	} $else $if linux && !musl ? {
+		return u64(C.gettid())
+	} $else $if threads {
+		return u64(C.pthread_self())
+	} $else {
+		return v_getpid()
+	}
+}

vlib/builtin/builtin_test.c.v

@@ -18,3 +18,10 @@ fn test_bool_size() {
 	println(@LOCATION)
 	assert sizeof(C.BOOL) == 4
 }
+
+fn test_v_getpid__and__v_gettid() {
+	p := v_getpid()
+	dump(p)
+	t := v_gettid()
+	dump(t)
+}

vlib/builtin/cfns.c.v

@@ -105,11 +105,14 @@ fn C.strchr(s &char, c int) &char
 
 // process execution, os.process:
 @[trusted]
+fn C.GetCurrentProcessId() u32
+@[trusted]
+fn C._getpid() int
+@[trusted]
 fn C.getpid() int
 
 @[trusted]
 fn C.GetCurrentThreadId() u32
-
 @[trusted]
 fn C.gettid() u32
 

vlib/v/gen/native/comptime.v

@@ -216,6 +216,9 @@ fn (mut g Gen) comptime_ident(name string, is_comptime_option bool) bool {
 		'no_main' {
 			g.pref.is_script
 		}
+		'threads' {
+			true
+		}
 		else {
 			if is_comptime_option
 				|| (g.pref.compile_defines_all.len > 0 && name in g.pref.compile_defines_all) {