remove redis server-side hashing for performance

we still  compute the document hash in node, and check it on retrieval
but we don't check the hash at the point of writing it in redis which
was previously done with a redis Lua script.

services/document-updater/app/coffee/RedisManager.coffee

@@ -15,16 +15,8 @@ MAX_REDIS_REQUEST_LENGTH = 5000 # 5 seconds
 # Make times easy to read
 minutes = 60 # seconds for Redis expire
 
-# LUA script to write document and return hash
-# arguments: docLinesKey docLines
-setScript = """
-	redis.call('set', KEYS[1], ARGV[1])
-	return redis.sha1hex(ARGV[1])
-"""
-
 logHashErrors = Settings.documentupdater?.logHashErrors
 logHashReadErrors = logHashErrors?.read
-logHashWriteErrors = logHashErrors?.write
 
 MEGABYTES = 1024 * 1024
 MAX_RANGES_SIZE = 3 * MEGABYTES
@@ -52,7 +44,7 @@ module.exports = RedisManager =
 				logger.error {err: error, doc_id, project_id}, error.message
 				return callback(error)
 			multi = rclient.multi()
-			multi.eval setScript, 1, keys.docLines(doc_id:doc_id), docLines
+			multi.set keys.docLines(doc_id:doc_id), docLines
 			multi.set keys.projectKey({doc_id:doc_id}), project_id
 			multi.set keys.docVersion(doc_id:doc_id), version
 			multi.set keys.docHash(doc_id:doc_id), docHash
@@ -64,10 +56,6 @@ module.exports = RedisManager =
 			multi.set keys.projectHistoryId(doc_id:doc_id), projectHistoryId
 			multi.exec (error, result) ->
 				return callback(error) if error?
-				# check the hash computed on the redis server
-				writeHash = result?[0]
-				if logHashWriteErrors and writeHash? and writeHash isnt docHash
-					logger.error project_id: project_id, doc_id: doc_id, writeHash: writeHash, origHash: docHash, docLines:docLines, "hash mismatch on putDocInMemory"
 				# update docsInProject set
 				rclient.sadd keys.docsInProject(project_id:project_id), doc_id, callback
 
@@ -247,7 +235,7 @@ module.exports = RedisManager =
 					logger.error err: error, doc_id: doc_id, ranges: ranges, error.message
 					return callback(error)
 				multi = rclient.multi()
-				multi.eval setScript, 1, keys.docLines(doc_id:doc_id), newDocLines  # index 0
+				multi.set    keys.docLines(doc_id:doc_id), newDocLines  # index 0
 				multi.set    keys.docVersion(doc_id:doc_id), newVersion             # index 1
 				multi.set    keys.docHash(doc_id:doc_id), newHash                   # index 2
 				multi.ltrim  keys.docOps(doc_id: doc_id), -RedisManager.DOC_OPS_MAX_LENGTH, -1 # index 3
@@ -272,10 +260,6 @@ module.exports = RedisManager =
 						multi.del keys.lastUpdatedBy(doc_id: doc_id) # index 9
 				multi.exec (error, result) ->
 						return callback(error) if error?
-						# check the hash computed on the redis server
-						writeHash = result?[0]
-						if logHashWriteErrors and writeHash? and writeHash isnt newHash
-							logger.error doc_id: doc_id, writeHash: writeHash, origHash: newHash, docLines:newDocLines, "hash mismatch on updateDocument"
 
 						# length of uncompressedHistoryOps queue (index 7)
 						docUpdateCount = result[7]

services/document-updater/test/unit/coffee/RedisManager/RedisManagerTests.coffee

@@ -351,7 +351,6 @@ describe "RedisManager", ->
 			@multi.expire = sinon.stub()
 			@multi.ltrim = sinon.stub()
 			@multi.del = sinon.stub()
-			@multi.eval = sinon.stub()
 			@multi.exec = sinon.stub().callsArgWith(0, null,
 				[@hash, null, null, null, null, null, null, @doc_update_list_length, null, null]
 			)
@@ -374,8 +373,8 @@ describe "RedisManager", ->
 						.should.equal true
 
 				it "should set the doclines", ->
-					@multi.eval
-						.calledWith(sinon.match(/redis.call/), 1, "doclines:#{@doc_id}", JSON.stringify(@lines))
+					@multi.set
+						.calledWith("doclines:#{@doc_id}", JSON.stringify(@lines))
 						.should.equal true
 
 				it "should set the version", ->
@@ -486,8 +485,8 @@ describe "RedisManager", ->
 					.should.equal false
 
 			it "should still set the doclines", ->
-				@multi.eval
-					.calledWith(sinon.match(/redis.call/), 1, "doclines:#{@doc_id}", JSON.stringify(@lines))
+				@multi.set
+					.calledWith("doclines:#{@doc_id}", JSON.stringify(@lines))
 					.should.equal true
 
 		describe "with empty ranges", ->
@@ -505,20 +504,6 @@ describe "RedisManager", ->
 					.calledWith("Ranges:#{@doc_id}")
 					.should.equal true
 
-		describe "with a corrupted write", ->
-			beforeEach ->
-				@badHash = "INVALID-HASH-VALUE"
-				@multi.exec = sinon.stub().callsArgWith(0, null, [@badHash])
-				@RedisManager.getDocVersion.withArgs(@doc_id).yields(null, @version - @ops.length)
-				@RedisManager.updateDocument @project_id, @doc_id, @lines, @version, @ops, @ranges, @updateMeta, @callback
-
-			it 'should log a hash error', ->
-				@logger.error.calledWith()
-					.should.equal true
-
-			it "should call the callback", ->
-				@callback.called.should.equal true
-
 		describe "with null bytes in the serialized doc lines", ->
 			beforeEach ->
 				@RedisManager.getDocVersion.withArgs(@doc_id).yields(null, @version - @ops.length)
@@ -567,7 +552,6 @@ describe "RedisManager", ->
 			@multi.set = sinon.stub()
 			@rclient.sadd = sinon.stub().yields()
 			@multi.del = sinon.stub()
-			@multi.eval = sinon.stub()
 			@lines = ["one", "two", "three", "これは"]
 			@version = 42
 			@hash = crypto.createHash('sha1').update(JSON.stringify(@lines),'utf8').digest('hex')
@@ -580,8 +564,8 @@ describe "RedisManager", ->
 				@RedisManager.putDocInMemory @project_id, @doc_id, @lines, @version, @ranges, @pathname, @projectHistoryId, done
 
 			it "should set the lines", ->
-				@multi.eval
-					.calledWith(sinon.match(/redis.call/), 1, "doclines:#{@doc_id}", JSON.stringify(@lines))
+				@multi.set
+					.calledWith("doclines:#{@doc_id}", JSON.stringify(@lines))
 					.should.equal true
 
 			it "should set the version", ->
@@ -637,15 +621,6 @@ describe "RedisManager", ->
 					.calledWith("Ranges:#{@doc_id}", JSON.stringify(@ranges))
 					.should.equal false
 
-		describe "with a corrupted write", ->
-			beforeEach (done) ->
-				@multi.exec = sinon.stub().callsArgWith(0, null, ["INVALID-HASH-VALUE"])
-				@RedisManager.putDocInMemory @project_id, @doc_id, @lines, @version, @ranges, @pathname, @projectHistoryId, done
-
-			it 'should log a hash error', ->
-				@logger.error.calledWith()
-					.should.equal true
-
 		describe "with null bytes in the serialized doc lines", ->
 			beforeEach ->
 				@_stringify = JSON.stringify