Add query/mutation logging in glog V=3.

[danielmai]

Closes #4944.

By setting -v=3 or --vmodule=server=3, then query/mutation logs will appear in the Alpha log.

Example:

Query (has query: field)

I0324 15:41:27.464042    9642 server.go:771] Got a query: query:"{ q(func: has(counter.val)) { uid, val: counter.val }}"

Mutation (has mutations: field)

I0324 15:41:27.474000    9642 server.go:771] Got a query: start_ts:20006 mutations:<set_nquads:"<0x1> <counter.val> \"11\"^^<xs:int> ." commit_now:true > commit_now:true

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This change is 

[sleto-it]

Needs doc. However new section about logs can be handled as part of DGRAPH-1165

[animesh2049]

Reviewable status: 0 of 1 files reviewed, all discussions resolved (waiting on @manishrjain)

[martinmr]

, just a question regarding new lines in the query.

Reviewed 1 of 1 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @danielmai and @manishrjain)

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edgraph/server.go, line 771 at r1 (raw file):

	resp *api.Response, rerr error) {
	if glog.V(3) {
		glog.Infof("Got a query: %+v", req)

will new lines in the query be printed as new lines in the log? If they do the query should be stripped of new lines to make sure the log is all in a single line.

[danielmai]

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edgraph/server.go, line 771 at r1 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

will new lines in the query be printed as new lines in the log? If they do the query should be stripped of new lines to make sure the log is all in a single line.

Good point. Logs are always in a single line. Queries have \n for newlines. e.g.,

I0401 19:59:26.541382      16 server.go:771] Got a query: query:"query {\n  getGQLSchema(func: type(dgraph.graphql)) {\n    id :
uid\n    schema : dgraph.graphql.schema\n    dgraph.uid : uid\n  }\n}" read_only:true