More Robust GC #3712

kevina · 2017-02-20T20:44:16Z

No description provided.

kevina · 2017-02-20T23:12:03Z

@whyrusleeping this is very much a work in progress, just want some early feedback.

kevina · 2017-02-20T23:18:48Z

This is based on #3700 use this link for a better comparison until that is merged: kevina/enumerate-children-refactor...kevina/more-robust-gc

kevina · 2017-02-23T07:54:45Z

This took longer than I would of like and I am not sure I am happy with the approach but it should work. Everything is tested, but the test could also use some improvements in order to document why what they are testing is important.

whyrusleeping · 2017-02-23T08:23:09Z

pin/gc/gc.go

 			}
 		}
+		if errors {
+			errOutput <- CouldNotDeleteSomeBlocksError


ErrCouldNotDeleteSomeBlocks

whyrusleeping · 2017-02-23T08:23:55Z

pin/gc/gc.go

@@ -22,58 +25,73 @@ var log = logging.Logger("gc")
 //
 // The routine then iterates over every block in the blockstore and
 // deletes any block that is not found in the marked set.
-func GC(ctx context.Context, bs bstore.GCBlockstore, ls dag.LinkService, pn pin.Pinner, bestEffortRoots []*cid.Cid) (<-chan *cid.Cid, error) {
+//
+func GC(ctx context.Context, bs bstore.GCBlockstore, ls dag.LinkService, pn pin.Pinner, bestEffortRoots []*cid.Cid) (<-chan *cid.Cid, <-chan error) {


I think a cleaner return value would be to return a channel of 'results'. Where a result would be defined as something like:

type Result struct { Cid *cid.Cid Err error }

Its always simpler to just have to deal with a single channel in cases like these, it can cause tricky race conditions (though the race conditions probably arent an issue here).

Yeah that is one of the things I didn't like also. Working on fixing that today.

whyrusleeping · 2017-02-23T08:25:26Z

pin/gc/gc.go

 	}
+}
+
+var CoundNotFetchAllLinksError = errors.New("garbage collection aborted: could not retrieve some links")


make sure errors like this have an Err prefix

whyrusleeping · 2017-02-23T08:25:53Z

test/sharness/t0087-repo-robust-gc.sh

+test_description="Test ipfs pinning operations"
+
+. lib/test-lib.sh
+set -e


Don't use set -e, sharness handles these sorts of things

(you can run the tests with -i to stop when a test fails)

I can remove it if you want, but note it does serve a very useful purpose. Please see #3721. I already know about -i and that is not why i am using it.

whyrusleeping · 2017-02-23T08:26:29Z

test/sharness/t0087-repo-robust-gc.sh

+# MIT Licensed; see the LICENSE file in this repository.
+#
+
+test_description="Test ipfs pinning operations"


probably want to update the description

whyrusleeping · 2017-02-23T08:29:05Z

test/sharness/t0087-repo-robust-gc.sh

+	LEAF4=zb2rhnvAVvfDDnndcfQkwqNgUm94ba3zBSXyJKCfVXwU4FXx
+
+	test_expect_success "remove a leaf node from the repo manually" '
+		rm $LEAF1FILE


quotes around the variable, just in case it changes

whyrusleeping · 2017-02-23T08:33:48Z

test/sharness/t0087-repo-robust-gc.sh

+
+	test_expect_success "create a permission problem" '
+		chmod 500 `dirname $LEAF2FILE` &&
+		test_must_fail ipfs block rm $LEAF2 2>&1 | tee err &&


probably fine just to redirect this to 'err'. May also want to name 'err' something a tiny bit more descriptive like 'block_rm_err'

So the reason I do it this was is so rather than a simple '2> err' is so that I can see the output of the command when developing the test. It is far easier than having to do a cat "trash directory XXX/err". The sharness framework will suppress both stdout and stderr from a test unless '-v' is given so I don't see extra noise as a problem. If the test does fail for some reason then it is helpful to see the output of the command without having to track down the output file name. If a test fails on a build server the output file may not even be accessible.

Nevertheless, I understand it is not the convention used in the other tests, so if you still don't like I it I will reluctantly change it after I am done developing the tests and the code. Let me know.

whyrusleeping · 2017-02-24T22:51:17Z

pin/gc/gc.go

 	} else {
 		return gcs, nil
 	}
 }

-var CoundNotFetchAllLinksError = errors.New("garbage collection aborted: could not retrieve some links")
+var ErrCoundNotFetchAllLinks = errors.New("garbage collection aborted: could not retrieve some links")


typo here (not sure if you fixed already, going through commit by commit)

whyrusleeping · 2017-02-24T22:55:15Z

test/sharness/t0087-repo-robust-gc.sh

@@ -37,6 +39,23 @@ test_gc_robust_part1() {
 		ipfs repo gc
 	'

+	test_expect_success "corrupt the root node of 1MB file" '
+		ls -l "$HASH1FILE"


Why is this ls here?

I was seeing something. Will remove.

whyrusleeping · 2017-02-24T22:55:58Z

test/sharness/t0087-repo-robust-gc.sh

+		grep -q "aborted" gc_err
+	'
+
+	test_expect_success "leaf nodes where not removed after gc" '


typo, s/where/were/

whyrusleeping · 2017-02-24T22:57:00Z

test/sharness/t0087-repo-robust-gc.sh

+
+	test_expect_success "leaf nodes where not removed after gc" '
+		ipfs cat $LEAF3 > /dev/null &&
+		ipfs cat $LEAF4 > /dev/null


Is this test run both with and without a daemon? If yes, we should add a --timeout flag here, if no, we should make sure to run this test with and without a daemon ;)

@whyrusleeping Um, that is what the "--offline" flag is for.

resolved via irc, no need for --timeout flag.

whyrusleeping · 2017-02-24T22:58:25Z

core/commands/repo.go


-		outChan := make(chan interface{})
+		outChan := make(chan interface{}, len(gcOutChan))


What does len on a channel tell us? Is it the capacity? or the number of items currently waiting in it?

Oops, should be cap. Sorry. Will fix.

whyrusleeping · 2017-02-24T22:59:53Z

core/commands/repo.go

-			default:
-				res.SetError(corerepo.NewMultiError(errors...), cmds.ErrNormal)
-				return
+			err := corerepo.CollectResult(gcOutChan, func(k *cid.Cid) {


Though you probably want to select with a context here to make sure there are no accidental hangs

@whyrusleeping I am never sure when I should be using a context and when it is okay to just read from a channel. When is checking for ctx.Done() important in the pipeline?

(discussed in IRC, putting here for posterity)

Any time youre sending or receiving on a channel that is outside the control of your immediate goroutine, its a good idea to use a context. In this case, the reader is the commands lib, and the commands lib will stop reading from the channel if the user cancels the operation.

whyrusleeping · 2017-02-24T23:08:45Z

core/commands/repo.go

@@ -51,6 +56,7 @@ order to reclaim hard disk space.
 	},
 	Options: []cmds.Option{
 		cmds.BoolOption("quiet", "q", "Write minimal output.").Default(false),
+		cmds.BoolOption("stream-errors", "Stream errors.").Default(false),


👍 I also like this. It is a good option.

whyrusleeping · 2017-02-24T23:10:14Z

pin/gc/gc.go

@@ -66,7 +66,7 @@ func GC(ctx context.Context, bs bstore.GCBlockstore, ls dag.LinkService, pn pin.
 					err := bs.DeleteBlock(k)
 					if err != nil {
 						errors = true
-						output <- Result{Error: &CouldNotDeleteBlockError{k, err}}
+						output <- Result{Error: &ErrCouldNotDeleteBlock{k, err}}


I think what you had originally was good. It seems the go convention for error types is to suffix them with the word Error.

https://golang.org/pkg/net/#DNSConfigError

Okay. Will revert that commit.

kevina · 2017-02-24T23:44:04Z

@whyrusleeping Okay, I address all your comments. I think this is ready. Will rebase once #3700 is merged.

whyrusleeping · 2017-02-25T00:08:44Z

@kevina great, thanks!

kevina · 2017-03-17T20:29:22Z

Thanks.

whyrusleeping · 2017-03-19T00:24:26Z

core/commands/repo.go

@@ -87,26 +110,29 @@ order to reclaim hard disk space.
 				return nil, err
 			}

-			marshal := func(v interface{}) (io.Reader, error) {
-				obj, ok := v.(*corerepo.KeyRemoved)
+			for v := range outChan {


This should still use the marshal func construction like it previously did. Output for stdout can go through the same style of returned pipe, and we can print to stderr within that.

The reason for this is to avoid the double error printing that you can see in @Kubuxu's sample output

I am not 100% sure I am following, but I attempted to do what you want. It did not seam to help with the duplicate error reporting.

@whyrusleeping for example here is the output from a test case when run with -v

expecting success: test_must_fail ipfs repo gc --stream-errors 2>&1 | tee repo_gc_out && grep -q "Error: could not retrieve links for $LEAF1" repo_gc_out && grep -q "Error: could not retrieve links for $LEAF2" repo_gc_out && grep -q "Error: garbage collection aborted" repo_gc_out Error: could not retrieve links for QmSijovevteoY63Uj1uC5b8pkpDU5Jgyk2dYBqz3sMJUPc: merkledag: not found Error: could not retrieve links for QmTbPEyrA1JyGUHFvmtx1FNZVzdBreMv8Hc8jV9sBRWhNA: The block referred to by 'QmTbPEyrA1JyGUHFvmtx1FNZVzdBreMv8Hc8jV9sBRWhNA' was not a valid merkledag node Error: garbage collection aborted: could not retrieve some links 01:35:09.788 ERROR commands/h: encountered errors during gc run client.go:247 Error: encountered errors during gc run ok 48 - 'ipfs repo gc --stream-errors' should abort and report each error separately

@whyrusleeping since using the marshal func construction didn't fix the double error reporting, do you still want to use the marshal func construction, I think it makes the code more complicated to understand. But I can leave it if you want.

License: MIT Signed-off-by: Kevin Atkinson <k@kevina.org>

hoenirvili · 2017-03-19T01:40:19Z

core/commands/repo.go

 				if !ok {
 					return nil, u.ErrCast()
 				}

-				buf := new(bytes.Buffer)
+				if obj.Error != "" {
+					fmt.Fprintf(res.Stderr(), "Error: %s\n", obj.Error)


Why use fmt.Fprintf and not use a standard ipfs logger?

The intent was for the output to go to the client's stderr. The logger won't do thus as far as I know.

Yes, this part of code runs on Client CLI (IIRC) not on the daemon so we are handling logging/errors manually here.

hoenirvili · 2017-03-19T01:42:42Z

core/commands/repo.go

@@ -39,6 +40,11 @@ var RepoCmd = &cmds.Command{
 	},
 }

+type GcResult struct {


Every type exported and every attribute that's also exported should have a well described comment above.

hoenirvili · 2017-03-19T01:44:05Z

core/corerepo/gc.go


+func CollectResult(ctx context.Context, gcOut <-chan gc.Result, cb func(*cid.Cid)) error {


Please add here also a doc string above the function name.

// CollectResult collects the output of a garbage collection run and calls the given callback for each object removed. It also collects all errors into a MultiError which is returned after the gc is completed

hoenirvili · 2017-03-19T01:44:38Z

core/corerepo/gc.go

+	return &MultiError{errs[:len(errs)-1], errs[len(errs)-1]}
+}
+
+type MultiError struct {


Doc string.

Also you could tell that the type implements the Error interface.

Mentioning that it implements the error interface is pretty redundant and not standard go convention

hoenirvili · 2017-03-19T01:44:41Z

core/corerepo/gc.go

-	roots, err := BestEffortRoots(n.FilesRoot)
-	if err != nil {
-		return nil, err
+func NewMultiError(errs ...error) *MultiError {


Doc string.

// NewMultiError creates a new MultiError object from a given slice of errors

hoenirvili · 2017-03-19T01:45:48Z

pin/gc/gc.go

@@ -14,6 +16,11 @@ import (

 var log = logging.Logger("gc")

+type Result struct {


Doc string.

// Result represents an incremental output from a garbage collection run. It contains either an error, or the cid of a removed object

hoenirvili · 2017-03-19T01:46:06Z

pin/gc/gc.go

@@ -83,35 +103,74 @@ func Descendants(ctx context.Context, getLinks dag.GetLinks, set *cid.Set, roots
 	return nil
 }

-func ColoredSet(ctx context.Context, pn pin.Pinner, ls dag.LinkService, bestEffortRoots []*cid.Cid) (*cid.Set, error) {
+func ColoredSet(ctx context.Context, pn pin.Pinner, ls dag.LinkService, bestEffortRoots []*cid.Cid, output chan<- Result) (*cid.Set, error) {


Doc string.

// ColoredSet computes the set of nodes in the graph that are pinned by the pins in the given pinner

hoenirvili · 2017-03-19T01:47:24Z

pin/gc/gc.go

 	}
+}
+
+var ErrCouldNotFetchAllLinks = errors.New("garbage collection aborted: could not retrieve some links")


Exported fields should have a doc string. Also, can we have the name ErrCannotFetchLinks ?

hoenirvili · 2017-03-19T01:48:04Z

pin/gc/gc.go

+
+var ErrCouldNotFetchAllLinks = errors.New("garbage collection aborted: could not retrieve some links")
+
+var ErrCouldNotDeleteSomeBlocks = errors.New("garbage collection incomplete: could not delete some blocks")


Doc string and can we have ErrCannotDeleteBlocks ?

hoenirvili · 2017-03-19T01:48:16Z

pin/gc/gc.go

+
+var ErrCouldNotDeleteSomeBlocks = errors.New("garbage collection incomplete: could not delete some blocks")
+
+type CouldNotFetchLinksError struct {


Doc string.

hoenirvili · 2017-03-19T01:48:25Z

pin/gc/gc.go

+	Err error
+}
+
+func (e *CouldNotFetchLinksError) Error() string {


Doc string.

hoenirvili · 2017-03-19T01:48:33Z

pin/gc/gc.go

+	return fmt.Sprintf("could not retrieve links for %s: %s", e.Key, e.Err)
+}
+
+type CouldNotDeleteBlockError struct {


Doc string.

hoenirvili · 2017-03-19T01:51:18Z

pin/gc/gc.go

+
+	if errors {
+		return nil, ErrCouldNotFetchAllLinks
+	} else {


You can dropthe else stmt.

This should look like

if errors { return nil, ErrCouldNotFetchAllLinks } return gcs, nil

whyrusleeping · 2017-03-19T02:25:37Z

core/commands/repo.go

@@ -39,6 +40,12 @@ var RepoCmd = &cmds.Command{
 	},
 }

+// GcResult is the result returned by "repo gc" command
+type GcResult struct {


We can actually remove this whole type in favor of the one in the gc package (just change the field names so the json marshaling matches up correctly)

The problem is we can't pass the error type through the API. I get:

02:40:33.946 ERROR commands/h: json: cannot unmarshal object into Go value of type error client.go:247 Error: json: cannot unmarshal object into Go value of type error

Fair, lets figure that out later then

whyrusleeping · 2017-03-20T17:53:20Z

@Kubuxu the circleCI failure here is the iptb failed to connect problem again. Didnt you have an idea on why that was happening?

Kubuxu · 2017-03-20T18:39:48Z

@whyrusleeping nope, couldn't figure it out. It happens much more on Travis and Circle than our CI which means it might be some race or instability.

I tried to replicate it locally (1000 runs) didn't find even one failure.

License: MIT Signed-off-by: Kevin Atkinson <k@kevina.org>

whyrusleeping

Travis flakiness aside, this LGTM.

Thanks @kevina, making GC better has been needed for a while now.

kevina · 2017-03-28T04:18:53Z

Yes I can, I have snapper running so have snapshots of this repo before repofix. I will archive it on my PC when I get back to my studio (Sunday), and then I can expose it for you over 60Mbit/s uplink pipe if you want to download it.

@Kubuxu did you ever do this.

I am very surprised you can't just remove the broken pins with the latest IPFS version. See #3796 (comment)

kevina added the status/in-progress In progress label Feb 20, 2017

whyrusleeping self-requested a review February 20, 2017 23:10

kevina mentioned this pull request Feb 21, 2017

ipfs repo gc fails with Error: unrecognized object type: %!s(uint64=114) #3553

Closed

kevina force-pushed the kevina/more-robust-gc branch from cc305ec to 886ac2f Compare February 22, 2017 01:18

whyrusleeping reviewed Feb 23, 2017

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pin/gc/gc.go Outdated

}

}

if errors {

errOutput <- CouldNotDeleteSomeBlocksError

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ErrCouldNotDeleteSomeBlocks

whyrusleeping reviewed Feb 23, 2017

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kevina force-pushed the kevina/more-robust-gc branch 2 times, most recently from 4a71e51 to cdccbae Compare February 24, 2017 22:13

Kubuxu mentioned this pull request Feb 24, 2017

Jenkins location is wrong ipfs-inactive/jenkins#46

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whyrusleeping reviewed Feb 24, 2017

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kevina force-pushed the kevina/more-robust-gc branch from cdccbae to 9cfba7d Compare February 24, 2017 23:29

kevina changed the title ~~WIP: More Robust GC~~ More Robust GC Feb 24, 2017

kevina force-pushed the kevina/more-robust-gc branch from a40d15c to b95e413 Compare February 24, 2017 23:51

whyrusleeping reviewed Mar 19, 2017

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gc: continue to use cmds.ChannelMarshaler

f66ca2f

License: MIT Signed-off-by: Kevin Atkinson <k@kevina.org>

hoenirvili reviewed Mar 19, 2017

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pin/gc/gc.go Outdated

Err error

}

func (e *CouldNotFetchLinksError) Error() string {

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Doc string.

hoenirvili reviewed Mar 19, 2017

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kevina force-pushed the kevina/more-robust-gc branch from bfaba39 to bdd0674 Compare March 19, 2017 02:21

whyrusleeping reviewed Mar 19, 2017

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kevina force-pushed the kevina/more-robust-gc branch 2 times, most recently from 39b2f74 to fbc4f90 Compare March 19, 2017 03:35

gc: address CR comments

d39d9ed

License: MIT Signed-off-by: Kevin Atkinson <k@kevina.org>

kevina force-pushed the kevina/more-robust-gc branch from fbc4f90 to d39d9ed Compare March 20, 2017 18:46

whyrusleeping approved these changes Mar 21, 2017

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whyrusleeping merged commit 21072a5 into master Mar 22, 2017

whyrusleeping deleted the kevina/more-robust-gc branch March 22, 2017 00:16

kevina mentioned this pull request Aug 28, 2017

Next generation of GC #4149

Closed


		outChan := make(chan interface{})
		outChan := make(chan interface{}, len(gcOutChan))


		func CollectResult(ctx context.Context, gcOut <-chan gc.Result, cb func(*cid.Cid)) error {

		@@ -14,6 +16,11 @@ import (

		var log = logging.Logger("gc")

		type Result struct {


		var ErrCouldNotFetchAllLinks = errors.New("garbage collection aborted: could not retrieve some links")

		var ErrCouldNotDeleteSomeBlocks = errors.New("garbage collection incomplete: could not delete some blocks")


		var ErrCouldNotDeleteSomeBlocks = errors.New("garbage collection incomplete: could not delete some blocks")

		type CouldNotFetchLinksError struct {

More Robust GC #3712

More Robust GC #3712

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kevina commented Feb 20, 2017

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