fossil-acid

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

// pick up the common data structures

rc("cd /sys/src/cmd/fossil; mk 9fsys.acid");
include("/sys/src/cmd/fossil/9fsys.acid");
rc("cd /sys/src/cmd/fossil; mk cache.acid");
include("/sys/src/cmd/fossil/cache.acid");
rc("cd /sys/src/cmd/fossil; mk disk.acid");
include("/sys/src/cmd/fossil/disk.acid");
rc("cd /sys/src/cmd/fossil; mk fs.acid");
include("/sys/src/cmd/fossil/fs.acid");
rc("cd /sys/src/libventi; mk plan9-thread.acid");
include("/sys/src/libventi/plan9-thread.acid");

// make a list of pids from a list of Thread structures
defn _threadlist(t)
{
	local l;

	l = {};
	while t do {
		t = (Thread)t;
		l = append l, t.pid;
		t = t.next;
	}
	return l;
}

// print info about a VtRendez
defn vtrendez(r)
{
	local l, t, w, q;

	r = (VtRendez)r;
	w = _threadlist(r.wfirst);
	if match(pid, w) >= 0 then
		print("\twaiting for wakeup\n");

	l = (VtLock)r.lk;
	q = _threadlist(l.qfirst);
	if match(pid, q) >= 0 then
		print("\tawakened; waiting for lock\n");

	print("\tr=(VtRendez)", r\X, "\n");
	print("\tl=(VtLock)", l\X, "\n");
	if l.writer != 0 then {
		t = (Thread)l.writer;
		print("\tvtLock is held by ", t.pid\D, "\n");
	}
}

// print info about a VtLock
defn vtlock(l)
{
	local t;

	l = (VtLock)l;
	print("\tl=(VtLock)", l\X, "\n");
	if l.writer then {
		t = (Thread)l.writer;
		print("\tvtLock is held by ", t.pid\D, "\n");
	} else if l.readers then
		print("\tvtLock is held by ", l.readers\D, " readers\n");
	else 
		print("\tvtLock is not held!\n");
}

// try to say something intelligent about why a process is stuck.
_pauses = {
	open,
	pread,
	pwrite,
	sleep,
	vtSleep,
	vtLock,
	vtRLock,
};

defn deadlocklist(l)
{
	while l do {
		setproc(head l);
		deadlock();
		l = tail l;
	}
}

defn deadlock()
{
	local stk, frame, name, stallframe, fossilframe, stallname;

	stk = strace(*PC, *SP, linkreg(0));

	print("setproc(", pid, ") // ", readfile("/proc/"+itoa(pid)+"/args"), "\n");
	stallframe = 0;
	stallname = "";
	fossilframe = 0;
	frame = {0};
	while stk do {
		lastframe = frame;
		frame = head stk;
		name = fmt(frame[0], 'a');
		if !stallframe && match(name, _pauses) >= 0 then {
			stallframe = frame;
			stallname = name;
			print("\t", fmt(frame[0], 'a'), "(");
			params(frame[2]);
			print(") ", pcfile(frame[0]), ":", pcline(frame[0]));
			print("\n\t\tcalled from ", fmt(frame[1], 'a'), " ");
			pfl(frame[1]);
		}
		if !fossilframe && regexp("^/sys/src/cmd/fossil/.*", pcfile(frame[0])) then {
			if !stallframe then {
				stallframe = lastframe;
				stallname = fmt(lastframe[0], 'a');
				print("\tunexpected stall: ", stallname, "\n");
				if match(stallname, _pauses) >= 0 then
					print("\t\t but it matches!\n");
			}
			fossilframe = frame;
			print("\t", fmt(frame[0], 'a'), "(");
			params(frame[2]);
			print(") ", pcfile(frame[0]), ":", pcline(frame[0]));
			print("\n\t\tcalled from ", fmt(frame[1], 'a'), " ");
			pfl(frame[1]);

			if name == cacheLocalLookup && stallname == vtLock then
				print("\twaiting to lock block b=(Block)", *cacheLocalLookup:b\X, "\n");
			if name == cacheLocal && stallname == vtSleep then
				print("\tsleeping on block b=(Block)", *cacheLocal:b\X, "\n");
			if name == blockWrite && stallname == vtSleep then
				print("\tsleeping on block b=(Block)", *blockFlush:b\X, "\n");
		}
		stk = tail stk;
	}

	if stallname == vtSleep then
		vtrendez(*vtSleep:q);
	if stallname == vtLock then
		vtlock(*vtLock:p);
	if !stallframe || !fossilframe then {
		print("\tconfused:");
		if !stallframe then print(" stallframe?");
		if !fossilframe then print(" fossilframe?");
		print("\n");
	}
	print("\n");
}

// fetch fsys
defn
fsysGet(name)
{
	return fsysmain;
}

// dump information about the cache
defn
cacheDump(c)
{
	local i, b, x;

	c = (Cache)c;
	x = c.blocks;
	i=0;
	loop 1,c.nblocks do {
		b = (Block)(x+i);
		print(b\X, " ", b.pc\X, " ", b.ref\D, "\n");
		i = i+sizeofBlock;
	}
}

// print block info
defn
printblist(bl)
{
	bl = (BList)bl;
	while bl != 0 do {
		print("[", bl.part\D, " ", bl.addr\X, " ", bl.vers\D, "]");
		bl = bl.next;
		if bl != 0 then
			print(", ");
	}
}

defn
block(b)
{
	local i;
	
	b = (Block)b;
	print("b=(Block)", b\X, "\n");
	print("\tref ", b.ref\D, " nlock ", b.nlock\D, "\n");
	print("\tpav=[", b.part\D, " ", b.addr\X, " ", b.vers\D, "]\n");
	print("\tprior=");
	printblist(b.prior);
	print("\n");
	print("\tunlink=");
	printblist(b.uhead);
	print("\n");
}