return error if the vlog writes exceeds more that 4GB.

[poonai]

This PR check whether vlog writes are bigger than 4GB. If it's bigger than 4GB, it returns an error.
Signed-off-by: பாலாஜி balaji@dgraph.io

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This change is 

[ashish-goswami]

Reviewable status: 0 of 2 files reviewed, 4 unresolved discussions (waiting on @ashish-goswami, @balajijinnah, @jarifibrahim, and @manishrjain)

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value.go, line 49 at r1 (raw file):

// maxVlogFileSize is the maximum size of the vlog file which can be created. Vlog Offset is of
// uint32, so limiting at max uint32

full stop.

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value.go, line 1371 at r1 (raw file):

}

// validateWrites will check whether the given request can fit into 4GB vlog file.

*requests

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value.go, line 1390 at r1 (raw file):

			continue
		}
		// estimated vlog offset will become current vlog offset if the vlog is not rotated.

*Estimated

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value.go, line 1410 at r1 (raw file):

		return nil
	}
	// validate writes before writing to vlog. Because, we don't want to partially write and return

*Validate

[poonai]

Reviewable status: 0 of 2 files reviewed, 4 unresolved discussions (waiting on @ashish-goswami, @jarifibrahim, and @manishrjain)

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value.go, line 49 at r1 (raw file):

Previously, ashish-goswami (Ashish Goswami) wrote…

full stop.

Done.

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value.go, line 1371 at r1 (raw file):

Previously, ashish-goswami (Ashish Goswami) wrote…

*requests

Done.

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value.go, line 1390 at r1 (raw file):

Previously, ashish-goswami (Ashish Goswami) wrote…

*Estimated

Done.

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value.go, line 1410 at r1 (raw file):

Previously, ashish-goswami (Ashish Goswami) wrote…

*Validate

Done.

[jarifibrahim]

Reviewable status: 0 of 2 files reviewed, 6 unresolved discussions (waiting on @ashish-goswami, @balajijinnah, @jarifibrahim, and @manishrjain)

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value.go, line 1381 at r2 (raw file):

		estimatedVlogOffset := vlogOffset + size
		if estimatedVlogOffset > uint64(maxVlogFileSize) {
			return errors.Errorf("Request size is bigger than %d", maxVlogFileSize)

Put the actual value as well. Request size %d is bigger than %d

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value_test.go, line 1243 at r2 (raw file):

func TestValidateWrite(t *testing.T) {
	// Mocking the file size, so that we don't allocate big memory while running test.
	maxVlogFileSize = 400

You should reset this value in a defer call otherwise other tests will fail.

[parasssh]

but get LGTM from Ibrahim as well.

Reviewable status: 0 of 2 files reviewed, 6 unresolved discussions (waiting on @ashish-goswami, @balajijinnah, and @manishrjain)