SWIFT-1293 Add support for loadBalanced option

Sources/MongoSwift/ConnectionString.swift

@@ -76,10 +76,6 @@ internal class ConnectionString {
             self.readConcern = rc
         }
 
-        if let replicaSet = options?.replicaSet {
-            try self.setUTF8Option(MONGOC_URI_REPLICASET, to: replicaSet)
-        }
-
         if let rr = options?.retryReads {
             try self.setBoolOption(MONGOC_URI_RETRYREADS, to: rr)
         }
@@ -360,24 +356,15 @@ internal class ConnectionString {
 
     /// Sets and validates SDAM-related on the underlying `mongoc_uri_t`.
     private func applyAndValidateSDAMOptions(_ options: MongoClientOptions?) throws {
+        // First, apply all the options...
+
+        if let replicaSet = options?.replicaSet {
+            try self.setUTF8Option(MONGOC_URI_REPLICASET, to: replicaSet)
+        }
+
         // Per SDAM spec: If the ``directConnection`` option is not specified, newly developed drivers MUST behave as
         // if it was specified with the false value.
         if let dc = options?.directConnection {
-            guard !(dc && self.usesDNSSeedlistFormat) else {
-                throw MongoError.InvalidArgumentError(
-                    message: "\(MONGOC_URI_DIRECTCONNECTION)=true is incompatible with mongodb+srv connection strings"
-                )
-            }
-
-            if let hosts = self.hosts {
-                guard !(dc && hosts.count > 1) else {
-                    throw MongoError.InvalidArgumentError(
-                        message: "\(MONGOC_URI_DIRECTCONNECTION)=true is incompatible with multiple seeds. " +
-                            "got seeds: \(hosts)"
-                    )
-                }
-            }
-
             try self.setBoolOption(MONGOC_URI_DIRECTCONNECTION, to: dc)
         } else if !self.hasOption(MONGOC_URI_DIRECTCONNECTION) {
             try self.setBoolOption(MONGOC_URI_DIRECTCONNECTION, to: false)
@@ -399,6 +386,52 @@ internal class ConnectionString {
 
             try self.setInt32Option(MONGOC_URI_HEARTBEATFREQUENCYMS, to: value)
         }
+
+        if let loadBalanced = options?.loadBalanced {
+            try self.setBoolOption(MONGOC_URI_LOADBALANCED, to: loadBalanced)
+        }
+
+        // Then, validate them...
+        let lb = self.options?[MONGOC_URI_LOADBALANCED]?.boolValue
+        let dc = self.options?[MONGOC_URI_DIRECTCONNECTION]?.boolValue
+        let hosts = self.hosts ?? []
+
+        if dc == true {
+            guard !self.usesDNSSeedlistFormat else {
+                throw MongoError.InvalidArgumentError(
+                    message: "\(MONGOC_URI_DIRECTCONNECTION)=true is incompatible with mongodb+srv connection strings"
+                )
+            }
+
+            guard lb != true else {
+                throw MongoError.InvalidArgumentError(
+                    message: "\(MONGOC_URI_DIRECTCONNECTION)=true is incompatible with \(MONGOC_URI_LOADBALANCED)=true"
+                )
+            }
+
+            guard hosts.count <= 1 else {
+                throw MongoError.InvalidArgumentError(
+                    message: "\(MONGOC_URI_DIRECTCONNECTION)=true is incompatible with multiple seeds. " +
+                        "got seeds: \(hosts)"
+                )
+            }
+        }
+
+        if lb == true {
+            guard self.replicaSet == nil else {
+                throw MongoError.InvalidArgumentError(
+                    message: "\(MONGOC_URI_LOADBALANCED)=true is incompatible with replicaSet option: found option " +
+                        "\(MONGOC_URI_REPLICASET)=\(self.replicaSet ?? "")"
+                )
+            }
+
+            guard hosts.count <= 1 else {
+                throw MongoError.InvalidArgumentError(
+                    message: "\(MONGOC_URI_LOADBALANCED)=true is incompatible with multiple seeds. " +
+                        "got seeds: \(hosts)"
+                )
+            }
+        }
     }
 
     /// Sets and validates server selection-related on the underlying `mongoc_uri_t`.

Sources/MongoSwift/MongoClient.swift

@@ -40,6 +40,9 @@ public struct MongoClientOptions: CodingStrategyProvider {
     /// Defaults to 10 seconds (10,000 ms). Must be at least 500ms.
     public var heartbeatFrequencyMS: Int?
 
+    /// Indicates whether the driver is connecting to a load balancer.
+    public var loadBalanced: Bool?
+
     /// The size (in milliseconds) of the permitted latency window beyond the fastest round-trip time amongst all
     /// servers. By default, only servers within 15ms of the fastest round-trip time receive queries.
     public var localThresholdMS: Int?
@@ -145,6 +148,7 @@ public struct MongoClientOptions: CodingStrategyProvider {
         dateCodingStrategy: DateCodingStrategy? = nil,
         directConnection: Bool? = nil,
         heartbeatFrequencyMS: Int? = nil,
+        loadBalanced: Bool? = nil,
         localThresholdMS: Int? = nil,
         maxPoolSize: Int? = nil,
         readConcern: ReadConcern? = nil,
@@ -173,6 +177,7 @@ public struct MongoClientOptions: CodingStrategyProvider {
         self.dateCodingStrategy = dateCodingStrategy
         self.directConnection = directConnection
         self.heartbeatFrequencyMS = heartbeatFrequencyMS
+        self.loadBalanced = loadBalanced
         self.localThresholdMS = localThresholdMS
         self.maxPoolSize = maxPoolSize
         self.minHeartbeatFrequencyMS = nil

Tests/MongoSwiftTests/ConnectionStringTests.swift

@@ -109,11 +109,13 @@ let shouldWarnButLibmongocErrors: [String: [String]] = [
 
 // tests we skip because we don't support the specified behavior.
 let skipUnsupported: [String: [String]] = [
-    // we don't support maxIdleTimeMS.
     "connection-pool-options.json": [
+        // we don't support maxIdleTimeMS.
         "Too low maxIdleTimeMS causes a warning",
         "Non-numeric maxIdleTimeMS causes a warning",
-        "Valid connection pool options are parsed correctly"
+        "Valid connection pool options are parsed correctly",
+        // We don't support minPoolSize.
+        "minPoolSize=0 does not error"
     ],
     // requires maxIdleTimeMS
     "connection-options.json": [
@@ -581,5 +583,33 @@ final class ConnectionStringTests: MongoSwiftTestCase {
         // directConnection=true cannot be used with multiple seeds
         expect(try ConnectionString("mongodb://localhost:27017,localhost:27018", options: opts))
             .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+
+        // The cases where the conflicting options are all in the connection string are already covered by the URI
+        // options tests, so here we only check behavior for cases where 1+ option is specified via the options struct.
+
+        // loadBalanced=true cannot be used with multiple seeds
+        opts = MongoClientOptions(loadBalanced: true)
+        expect(try ConnectionString("mongodb://localhost:27017,localhost:27018", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+
+        // loadBalanced=true cannot be used with replica set option
+        expect(try ConnectionString("mongodb://localhost:27017/?replicaSet=xyz", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+        opts.replicaSet = "xyz"
+        expect(try ConnectionString("mongodb://localhost:27017", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+
+        // loadBalanced=true cannot be used with directConnection=true
+        opts = MongoClientOptions(directConnection: true, loadBalanced: true)
+        expect(try ConnectionString("mongodb://localhost:27017", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+
+        opts = MongoClientOptions(directConnection: true)
+        expect(try ConnectionString("mongodb://localhost:27017/?loadBalanced=true", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
+
+        opts = MongoClientOptions(loadBalanced: true)
+        expect(try ConnectionString("mongodb://localhost:27017/?directConnection=true", options: opts))
+            .to(throwError(errorType: MongoError.InvalidArgumentError.self))
     }
 }

Tests/Specs/uri-options/tests/connection-options.json

@@ -168,6 +168,76 @@
       "hosts": null,
       "auth": null,
       "options": {}
+    },
+    {
+      "description": "loadBalanced=true",
+      "uri": "mongodb://example.com/?loadBalanced=true",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "loadBalanced": true
+      }
+    },
+    {
+      "description": "loadBalanced=true with directConnection=false",
+      "uri": "mongodb://example.com/?loadBalanced=true&directConnection=false",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "loadBalanced": true,
+        "directConnection": false
+      }
+    },
+    {
+      "description": "loadBalanced=false",
+      "uri": "mongodb://example.com/?loadBalanced=false",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "loadBalanced": false
+      }
+    },
+    {
+      "description": "Invalid loadBalanced value",
+      "uri": "mongodb://example.com/?loadBalanced=1",
+      "valid": true,
+      "warning": true,
+      "hosts": null,
+      "auth": null,
+      "options": {}
+    },
+    {
+      "description": "loadBalanced=true with multiple hosts causes an error",
+      "uri": "mongodb://example1,example2/?loadBalanced=true",
+      "valid": false,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {}
+    },
+    {
+      "description": "loadBalanced=true with directConnection=true causes an error",
+      "uri": "mongodb://example.com/?loadBalanced=true&directConnection=true",
+      "valid": false,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {}
+    },
+    {
+      "description": "loadBalanced=true with replicaSet causes an error",
+      "uri": "mongodb://example.com/?loadBalanced=true&replicaSet=replset",
+      "valid": false,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {}
     }
   ]
 }

Tests/Specs/uri-options/tests/connection-pool-options.json

@@ -2,13 +2,15 @@
   "tests": [
     {
       "description": "Valid connection pool options are parsed correctly",
-      "uri": "mongodb://example.com/?maxIdleTimeMS=50000",
+      "uri": "mongodb://example.com/?maxIdleTimeMS=50000&maxPoolSize=5&minPoolSize=3",
       "valid": true,
       "warning": false,
       "hosts": null,
       "auth": null,
       "options": {
-        "maxIdleTimeMS": 50000
+        "maxIdleTimeMS": 50000,
+        "maxPoolSize": 5,
+        "minPoolSize": 3
       }
     },
     {
@@ -28,6 +30,28 @@
       "hosts": null,
       "auth": null,
       "options": {}
+    },
+    {
+      "description": "maxPoolSize=0 does not error",
+      "uri": "mongodb://example.com/?maxPoolSize=0",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "maxPoolSize": 0
+      }
+    },
+    {
+      "description": "minPoolSize=0 does not error",
+      "uri": "mongodb://example.com/?minPoolSize=0",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "minPoolSize": 0
+      }
     }
   ]
 }