delta/go-git.git/src/runtime/select.go, branch dev.inline

runtime: use typedmemclr for typed memory

2016-10-28T18:20:04+00:00

The hybrid barrier requires distinguishing typed and untyped memory
even when zeroing because the *current* contents of the memory matters
even when overwriting.

This commit introduces runtime.typedmemclr and runtime.memclrHasPointers
as a typed memory clearing functions parallel to runtime.typedmemmove.
Currently these simply call memclr, but with the hybrid barrier we'll
need to shade any pointers we're overwriting. These will provide us
with the necessary hooks to do so.

Updates #17503.

Change-Id: I74478619f8907825898092aaa204d6e4690f27e6
Reviewed-on: https://go-review.googlesource.com/31366
Reviewed-by: Keith Randall 
Reviewed-by: Rick Hudson

runtime: rename fastrand1 to fastrand

2016-08-30T23:59:21+00:00

Change-Id: I37706ff0a3486827c5b072c95ad890ea87ede847
Reviewed-on: https://go-review.googlesource.com/28210
Run-TryBot: Josh Bleecher Snyder 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

runtime: simplify mallocgc flag argument

2016-04-20T14:02:22+00:00

mallocgc can calculate noscan itself.  The only remaining
flag argument is needzero, so we just make that a boolean arg.

Fixes #15379

Change-Id: I839a70790b2a0c9dbcee2600052bfbd6c8148e20
Reviewed-on: https://go-review.googlesource.com/22290
Reviewed-by: Josh Bleecher Snyder 
Run-TryBot: Josh Bleecher Snyder 
TryBot-Result: Gobot Gobot

runtime: make execution error panic values implement the Error interface

2016-04-10T01:16:30+00:00

Make execution panics implement Error as
mandated by https://golang.org/ref/spec#Run_time_panics,
instead of panics with strings.

Fixes #14965

Change-Id: I7827f898b9b9c08af541db922cc24fa0800ff18a
Reviewed-on: https://go-review.googlesource.com/21214
Reviewed-by: Brad Fitzpatrick 
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

runtime: never pass stack pointers to gopark

2016-03-16T20:13:10+00:00

gopark calls the unlock function after setting the G to _Gwaiting.
This means it's generally unsafe to access the G's stack from the
unlock function because the G may start running on another P. Once we
start shrinking stacks concurrently, a stack shrink could also move
the stack the moment after it enters _Gwaiting and before the unlock
function is called.

Document this restriction and fix the two places where we currently
violate it.

This is unlikely to be a problem in practice for these two places
right now, but they're already skating on thin ice. For example, the
following sequence could in principle cause corruption, deadlock, or a
panic in the select code:

On M1/P1:
1. G1 selects on channels A and B.
2. selectgoImpl calls gopark.
3. gopark puts G1 in _Gwaiting.
4. gopark calls selparkcommit.
5. selparkcommit releases the lock on channel A.

On M2/P2:
6. G2 sends to channel A.
7. The send puts G1 in _Grunnable and puts it on P2's run queue.
8. The scheduler runs, selects G1, puts it in _Grunning, and resumes G1.
9. On G1, the sellock immediately following the gopark gets called.
10. sellock grows and moves the stack.

On M1/P1:
11. selparkcommit continues to scan the lock order for the next
channel to unlock, but it's now reading from a freed (and possibly
reused) stack.

This shouldn't happen in practice because step 10 isn't the first call
to sellock, so the stack should already be big enough. However, once
we start shrinking stacks concurrently, this reasoning won't work any
more.

For #12967.

Change-Id: I3660c5be37e5be9f87433cb8141bdfdf37fadc4c
Reviewed-on: https://go-review.googlesource.com/20038
Reviewed-by: Rick Hudson 
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot

runtime: put g.waiting list in lock order

2016-03-16T20:13:07+00:00

Currently the g.waiting list created by a select is in poll order.
However, nothing depends on this, and we're going to need access to
the channel lock order in other places shortly, so modify select to
put the waiting list in channel lock order.

For #12967.

Change-Id: If0d38816216ecbb37a36624d9b25dd96e0a775ec
Reviewed-on: https://go-review.googlesource.com/20037
Reviewed-by: Rick Hudson 
Reviewed-by: Keith Randall 
Run-TryBot: Austin Clements

runtime: use indexes for select lock order

2016-03-16T20:13:05+00:00

Currently the select lock order is a []*hchan. We're going to need to
refer to things other than the channel itself in lock order shortly,
so switch this to a []uint16 of indexes into the select cases. This
parallels the existing representation for the poll order.

Change-Id: I89262223fe20b4ddf5321592655ba9eac489cda1
Reviewed-on: https://go-review.googlesource.com/20036
Reviewed-by: Rick Hudson 
Reviewed-by: Keith Randall 
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot

runtime: record channel in sudog

2016-03-16T20:13:02+00:00

Given a G, there's currently no way to find the channel it's blocking
on. We'll need this information to fix a (probably theoretical) bug in
select and to implement concurrent stack shrinking, so record the
channel in the sudog.

For #12967.

Change-Id: If8fb63a140f1d07175818824d08c0ebeec2bdf66
Reviewed-on: https://go-review.googlesource.com/20035
Reviewed-by: Rick Hudson 
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot

runtime: improve comment on selectgo

2016-03-14T16:29:21+00:00

In particular, document that *sel is on the stack no matter what.

Change-Id: I1c264215e026c27721b13eedae73ec845066cdec
Reviewed-on: https://go-review.googlesource.com/20032
Reviewed-by: Rick Hudson

all: single space after period.

2016-03-02T00:13:47+00:00

The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.

This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:

$ perl -i -npe 's,^(\s*// .+[a-z]\.)  +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.)  +([A-Z])')
$ go test go/doc -update

Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike 
Reviewed-by: Dave Day 
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot