GODRIVER-836 Fix zLib compression

Fixes the CompressBytes method of ZlibCompressor to correctly
return a slice of compressed bytes. Also ensuresUncompressBytes
will correctly return a slice of uncompressed bytes. Previously
both methods would return slices of length 0.

New Compressors are initialized for every connection to avoid
race conditions with the zLib compressor.

Evergreen config is updated to run zlib tests for mongo
versions > 3.4. Snappy tests now only run for versions > 3.2.
Unit tests are added for compressors.

Change-Id: I4524027a1ed85eb698a75e528b56cfe56a4d6167

Author: tfogo

.evergreen/config.yml

@@ -394,8 +394,8 @@ tasks:
             AUTH: "noauth"
             SSL: "nossl"
 
-    - name: test-standalone-noauth-nossl-compression
-      tags: ["test", "standalone", "compression"]
+    - name: test-standalone-noauth-nossl-snappy-compression
+      tags: ["test", "standalone", "compression", "snappy"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -409,6 +409,21 @@ tasks:
             SSL: "nossl"
             MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
+    - name: test-standalone-noauth-nossl-zlib-compression
+      tags: ["test", "standalone", "compression", "zlib"]
+      commands:
+        - func: bootstrap-mongo-orchestration
+          vars:
+            TOPOLOGY: "server"
+            AUTH: "noauth"
+            SSL: "nossl"
+        - func: run-tests
+          vars:
+            TOPOLOGY: "server"
+            AUTH: "noauth"
+            SSL: "nossl"
+            MONGO_GO_DRIVER_COMPRESSOR: "zlib"
+
     - name: test-standalone-auth-ssl
       tags: ["test", "standalone", "authssl"]
       commands:
@@ -423,8 +438,8 @@ tasks:
             AUTH: "auth"
             SSL: "ssl"
 
-    - name: test-standalone-auth-ssl-compression
-      tags: ["test", "standalone", "authssl", "compression"]
+    - name: test-standalone-auth-ssl-snappy-compression
+      tags: ["test", "standalone", "authssl", "compression", "snappy"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -438,22 +453,23 @@ tasks:
             SSL: "ssl"
             MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
-    - name: test-replicaset-noauth-nossl
-      tags: ["test", "replicaset"]
+    - name: test-standalone-auth-ssl-zlib-compression
+      tags: ["test", "standalone", "authssl", "compression", "zlib"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
-            TOPOLOGY: "replica_set"
-            AUTH: "noauth"
-            SSL: "nossl"
+            TOPOLOGY: "server"
+            AUTH: "auth"
+            SSL: "ssl"
         - func: run-tests
           vars:
-            TOPOLOGY: "replica_set"
-            AUTH: "noauth"
-            SSL: "nossl"
+            TOPOLOGY: "server"
+            AUTH: "auth"
+            SSL: "ssl"
+            MONGO_GO_DRIVER_COMPRESSOR: "zlib"
 
-    - name: test-replicaset-noauth-nossl-compression
-      tags: ["test", "replicaset", "compression"]
+    - name: test-replicaset-noauth-nossl
+      tags: ["test", "replicaset"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -465,7 +481,6 @@ tasks:
             TOPOLOGY: "replica_set"
             AUTH: "noauth"
             SSL: "nossl"
-            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
     - name: test-replicaset-auth-ssl
       tags: ["test", "replicaset", "authssl"]
@@ -481,23 +496,22 @@ tasks:
             AUTH: "auth"
             SSL: "ssl"
 
-    - name: test-replicaset-auth-ssl-compression
-      tags: ["test", "replicaset", "authssl", "compression"]
+    - name: test-sharded-noauth-nossl
+      tags: ["test", "sharded"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
-            TOPOLOGY: "replica_set"
-            AUTH: "auth"
-            SSL: "ssl"
+            TOPOLOGY: "sharded_cluster"
+            AUTH: "noauth"
+            SSL: "nossl"
         - func: run-tests
           vars:
-            TOPOLOGY: "replica_set"
-            AUTH: "auth"
-            SSL: "ssl"
-            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
+            TOPOLOGY: "sharded_cluster"
+            AUTH: "noauth"
+            SSL: "nossl"
 
-    - name: test-sharded-noauth-nossl
-      tags: ["test", "sharded"]
+    - name: test-sharded-noauth-nossl-snappy-compression
+      tags: ["test", "sharded", "compression", "snappy"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -509,9 +523,10 @@ tasks:
             TOPOLOGY: "sharded_cluster"
             AUTH: "noauth"
             SSL: "nossl"
+            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
-    - name: test-sharded-noauth-nossl-compression
-      tags: ["test", "sharded", "compression"]
+    - name: test-sharded-noauth-nossl-zlib-compression
+      tags: ["test", "sharded", "compression", "zlib"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -523,7 +538,7 @@ tasks:
             TOPOLOGY: "sharded_cluster"
             AUTH: "noauth"
             SSL: "nossl"
-            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
+            MONGO_GO_DRIVER_COMPRESSOR: "zlib"
 
     - name: test-sharded-auth-ssl
       tags: ["test", "sharded", "authssl"]
@@ -539,8 +554,8 @@ tasks:
             AUTH: "auth"
             SSL: "ssl"
 
-    - name: test-sharded-auth-ssl-compression
-      tags: ["test", "sharded", "authssl", "compression"]
+    - name: test-sharded-auth-ssl-snappy-compression
+      tags: ["test", "sharded", "authssl", "compression", "snappy"]
       commands:
         - func: bootstrap-mongo-orchestration
           vars:
@@ -554,27 +569,32 @@ tasks:
             SSL: "ssl"
             MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
-    - name: test-enterprise-auth-plain
-      tags: ["test", "enterprise-auth"]
+    - name: test-sharded-auth-ssl-zlib-compression
+      tags: ["test", "sharded", "authssl", "compression", "zlib"]
       commands:
-        - func: run-enterprise-auth-tests
+        - func: bootstrap-mongo-orchestration
           vars:
-            MONGODB_URI: "${plain_auth_mongodb_uri}"
+            TOPOLOGY: "sharded_cluster"
+            AUTH: "auth"
+            SSL: "ssl"
+        - func: run-tests
+          vars:
+            TOPOLOGY: "sharded_cluster"
+            AUTH: "auth"
+            SSL: "ssl"
+            MONGO_GO_DRIVER_COMPRESSOR: "zlib"
 
-    - name: test-enterprise-auth-plain-compression
+    - name: test-enterprise-auth-plain
       tags: ["test", "enterprise-auth"]
       commands:
         - func: run-enterprise-auth-tests
           vars:
             MONGODB_URI: "${plain_auth_mongodb_uri}"
-            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
     - name: test-enterprise-auth-gssapi
       tags: ["test", "enterprise-auth"]
       commands:
         - func: run-enterprise-gssapi-auth-tests
-          vars:
-            MONGO_GO_DRIVER_COMPRESSOR: "snappy"
 
     - name: test-enterprise-auth-gssapi-service-host
       tags: ["test", "enterprise-auth"]
@@ -730,7 +750,19 @@ buildvariants:
     - name: ".test !.authssl !.enterprise-auth !.compression"
 
 - matrix_name: "tests-nonlegacy-servers"
-  matrix_spec: { version: ["3.2", "3.4", "3.6", "4.0", "latest"], os-ssl-32: "*" }
+  matrix_spec: { version: "3.2", os-ssl-32: "*" }
+  display_name: "${version} ${os-ssl-32}"
+  tasks:
+    - name: ".test !.enterprise-auth !.compression"
+
+- matrix_name: "tests-nonlegacy-servers-with-snappy-support"
+  matrix_spec: { version: "3.4", os-ssl-32: "*" }
+  display_name: "${version} ${os-ssl-32}"
+  tasks:
+    - name: ".test !.enterprise-auth !.zlib"
+
+- matrix_name: "tests-nonlegacy-servers-with-zlib-support"
+  matrix_spec: { version: ["3.6", "4.0", "latest"], os-ssl-32: "*" }
   display_name: "${version} ${os-ssl-32}"
   tasks:
     - name: ".test !.enterprise-auth"

mongo/client.go

@@ -24,11 +24,9 @@ import (
 	"go.mongodb.org/mongo-driver/x/mongo/driver/topology"
 	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
 	"go.mongodb.org/mongo-driver/x/network/command"
-	"go.mongodb.org/mongo-driver/x/network/compressor"
 	"go.mongodb.org/mongo-driver/x/network/connection"
 	"go.mongodb.org/mongo-driver/x/network/connstring"
 	"go.mongodb.org/mongo-driver/x/network/description"
-	"go.mongodb.org/mongo-driver/x/network/wiremessage"
 )
 
 const defaultLocalThreshold = 15 * time.Millisecond
@@ -209,40 +207,30 @@ func (c *Client) configure(opts *options.ClientOptions) error {
 		appName = *opts.AppName
 	}
 	// Compressors & ZlibLevel
-	var compressors []string
+	var comps []string
 	if len(opts.Compressors) > 0 {
-		compressors = opts.Compressors
-		comps := make([]compressor.Compressor, 0, len(compressors))
-
-		for _, c := range compressors {
-			switch c {
-			case "snappy":
-				comps = append(comps, compressor.CreateSnappy())
-			case "zlib":
-				level := wiremessage.DefaultZlibLevel
-				if opts.ZlibLevel != nil {
-					level = *opts.ZlibLevel
-				}
-				zlibComp, err := compressor.CreateZlib(level)
-				if err != nil {
-					return err
-				}
-				comps = append(comps, zlibComp)
-			}
-		}
+		comps = opts.Compressors
 
 		connOpts = append(connOpts, connection.WithCompressors(
-			func(compressors []compressor.Compressor) []compressor.Compressor {
+			func(compressors []string) []string {
 				return append(compressors, comps...)
 			},
 		))
 
+		for _, comp := range comps {
+			if comp == "zlib" {
+				connOpts = append(connOpts, connection.WithZlibLevel(func(level *int) *int {
+					return opts.ZlibLevel
+				}))
+			}
+		}
+
 		serverOpts = append(serverOpts, topology.WithCompressionOptions(
-			func(opts ...string) []string { return append(opts, compressors...) },
+			func(opts ...string) []string { return append(opts, comps...) },
 		))
 	}
 	// Handshaker
-	var handshaker connection.Handshaker = &command.Handshake{Client: command.ClientDoc(appName), Compressors: compressors}
+	var handshaker connection.Handshaker = &command.Handshake{Client: command.ClientDoc(appName), Compressors: comps}
 	// Auth & Database & Password & Username
 	if opts.Auth != nil {
 		cred := &auth.Cred{
@@ -271,7 +259,7 @@ func (c *Client) configure(opts *options.ClientOptions) error {
 		handshakeOpts := &auth.HandshakeOptions{
 			AppName:       appName,
 			Authenticator: authenticator,
-			Compressors:   compressors,
+			Compressors:   comps,
 		}
 		if mechanism == "" {
 			// Required for SASL mechanism negotiation during handshake

x/mongo/driver/topology/server.go

@@ -39,7 +39,7 @@ var ErrServerClosed = errors.New("server is closed")
 var ErrServerConnected = errors.New("server is connected")
 
 // SelectedServer represents a specific server that was selected during server selection.
-// It contains the kind of the typology it was selected from.
+// It contains the kind of the topology it was selected from.
 type SelectedServer struct {
 	*Server
 

x/mongo/driver/topology/topology_options.go

@@ -13,7 +13,6 @@ import (
 
 	"go.mongodb.org/mongo-driver/x/mongo/driver/auth"
 	"go.mongodb.org/mongo-driver/x/network/command"
-	"go.mongodb.org/mongo-driver/x/network/compressor"
 	"go.mongodb.org/mongo-driver/x/network/connection"
 	"go.mongodb.org/mongo-driver/x/network/connstring"
 )
@@ -191,26 +190,18 @@ func WithConnString(fn func(connstring.ConnString) connstring.ConnString) Option
 		}
 
 		if len(cs.Compressors) > 0 {
-			comp := make([]compressor.Compressor, 0, len(cs.Compressors))
-
-			for _, c := range cs.Compressors {
-				switch c {
-				case "snappy":
-					comp = append(comp, compressor.CreateSnappy())
-				case "zlib":
-					zlibComp, err := compressor.CreateZlib(cs.ZlibLevel)
-					if err != nil {
-						return err
-					}
+			connOpts = append(connOpts, connection.WithCompressors(func(compressors []string) []string {
+				return append(compressors, cs.Compressors...)
+			}))
 
-					comp = append(comp, zlibComp)
+			for _, comp := range cs.Compressors {
+				if comp == "zlib" {
+					connOpts = append(connOpts, connection.WithZlibLevel(func(level *int) *int {
+						return &cs.ZlibLevel
+					}))
 				}
 			}
 
-			connOpts = append(connOpts, connection.WithCompressors(func(compressors []compressor.Compressor) []compressor.Compressor {
-				return append(compressors, comp...)
-			}))
-
 			c.serverOpts = append(c.serverOpts, WithCompressionOptions(func(opts ...string) []string {
 				return append(opts, cs.Compressors...)
 			}))