Better config checks

README.md

@@ -77,7 +77,11 @@ export CGO_LDFLAGS_ALLOW="-Wl,-rpath.*"
 ### Windows
 
 * Install the Go runtime and compiler. On Windows, the common directory is `c:\Go`
-* Ensure you have a gcc-based compiler, for example from the Cygwin distribution. I use the mingw variation, to ensure compiled code can be used on systems without Cygwin installed
+* Ensure you have a gcc-based compiler, for example from the Cygwin distribution. 
+I recommend you use the mingw variation, to ensure compiled code can be used on systems without Cygwin installed. 
+The default `gcc` compiler from Cygwin does not work because it tries to build a
+Cygwin-enabled executable but the MQ libraries do not work in that model; 
+the `mingw` versions build Windows-native programs.
 * Create a working directory. For example, `mkdir c:\Gowork`
 * Set environment variables. Based on the previous lines,
 
@@ -99,11 +103,21 @@ set CC=x86_64-w64-mingw32-gcc.exe
   `git clone https://github.com/ibm-messaging/mq-golang.git src/github.com/ibm-messaging/mq-golang`
 
 * If you have not installed MQ libraries into the default location, then set environment variables
-for the C compiler to recognise those directories. For example,
+for the C compiler to recognise those directories. You may get messages from the compiler
+saying that the default MQ directories cannot be found, but those warnings can be ignored.
+The exact values for these environment variables will vary by platform, but follow the 
+corresponding CFLAGS/LDFLAGS values in `mqi.go`
+
+For example,
 
 ```
-   export CGO_CFLAGS="-I/my/mq/dir/inc"
-   export CGO_LDFLAGS="-I/my/mq/dir/lib64"
+   export MQ_INSTALLATION_PATH=/my/mq/dir  # This will also be set from the setmqenv command
+
+   export CGO_CFLAGS="-I$MQ_INSTALLATION_PATH/inc"
+
+   export CGO_LDFLAGS="-L$MQ_INSTALLATION_PATH/lib64 -Wl,rpath=$MQ_INSTALLATION_PATH/lib64"
+       or on Darwin
+   export CGO_LDFLAGS="-L$MQ_INSTALLATION_PATH/lib64 -Wl,rpath,$MQ_INSTALLATION_PATH/lib64"
 ```
 
 * Compile the `ibmmq` component:
@@ -144,4 +158,4 @@ in the CLA.
 
 ## Copyright
 
-© Copyright IBM Corporation 2016, 2018
+© Copyright IBM Corporation 2016, 2019

ibmmq/mqi.go

@@ -43,8 +43,8 @@ package ibmmq
 /*
 #cgo !windows CFLAGS: -I/opt/mqm/inc -D_REENTRANT
 #cgo  windows CFLAGS:  -I"C:/Program Files/IBM/MQ/Tools/c/include"
-#cgo !windows,!darwin LDFLAGS: -L/opt/mqm/lib64 -lmqm_r -Wl,-rpath=/opt/mqm/lib64 -Wl,-rpath=/usr/lib64
-#cgo darwin   LDFLAGS: -L/opt/mqm/lib64 -lmqm_r -Wl,-rpath,/opt/mqm/lib64 -Wl,-rpath=/usr/lib64
+#cgo !windows,!darwin LDFLAGS: -L/opt/mqm/lib64 -lmqm_r -Wl,-rpath,/opt/mqm/lib64 -Wl,-rpath,/usr/lib64
+#cgo darwin   LDFLAGS:         -L/opt/mqm/lib64 -lmqm_r -Wl,-rpath,/opt/mqm/lib64 -Wl,-rpath,/usr/lib64
 #cgo windows LDFLAGS: -L "C:/Program Files/IBM/MQ/bin64" -lmqm
 
 #include <stdlib.h>

mqmetric/discover.go

@@ -91,6 +91,7 @@ var Metrics AllMetrics
 
 var qList []string
 var locale string
+var discoveryDone = false
 
 func GetDiscoveredQueues() []string {
 	return qList
@@ -105,12 +106,60 @@ func SetLocale(l string) {
 }
 
 /*
-DiscoverAndSubscribe does all the work of finding the
+ * Check any important parameters  - this must be called after DiscoverAndSubscribe
+ * to maintain compatibility of the package's APIs.  It also needs the qList to have been
+ * populated first which is also done in DiscoverAndSubscribe.
+ * Returns: an MQ CompCode, error string. CompCode can be MQCC_OK, WARNING or ERROR.
+ */
+func VerifyConfig() (int32, error) {
+	var err error
+	var v map[int32]interface{}
+	var compCode = ibmmq.MQCC_OK
+	if !discoveryDone {
+		err = fmt.Errorf("Error: Need to call DiscoverAndSubscribe first")
+		compCode = ibmmq.MQCC_FAILED
+	}
+
+	if err == nil {
+		selectors := []int32{ibmmq.MQIA_MAX_Q_DEPTH, ibmmq.MQIA_DEFINITION_TYPE}
+		v, err = replyQObj.InqMap(selectors)
+		if err == nil {
+			maxQDepth := v[ibmmq.MQIA_MAX_Q_DEPTH].(int32)
+			// Function has tuning based on number of queues to be monitored
+			// Current published resource topics are approx 95 for qmgr
+			// ... and 35 per queue
+			// Make recommended minimum qdepth  60 / 10 * total per interval to allow one minute of data
+			// as MQ publications are at 10 second interval by default (and no public tuning)
+			// and monitor collection interval is one minute
+			recommendedDepth := (100 + len(qList)*50) * 6
+			if maxQDepth < int32(recommendedDepth) {
+				err = fmt.Errorf("Warning: Maximum queue depth on %s may be too low. Current value = %d", replyQBaseName, maxQDepth)
+				compCode = ibmmq.MQCC_WARNING
+			}
+
+			// Make sure this reply queue that has been opened is not a predefined queue, so it
+			// has come from a model definition. The base replyQ is opened twice for different reasons.
+			// A LOCAL queue would end up with mixed sets of replies/publications
+			defType := v[ibmmq.MQIA_DEFINITION_TYPE].(int32)
+			if defType == ibmmq.MQQDT_PREDEFINED {
+				err = fmt.Errorf("Error: ReplyQ parameter %s must refer to a MODEL queue,", replyQBaseName)
+				compCode = ibmmq.MQCC_FAILED
+			}
+		}
+	}
+	return compCode, err
+}
+
+/*
+DiscoverAndSubscribe does the work of finding the
 different resources available from a queue manager and
 issuing the MQSUB calls to collect the data
 */
 func DiscoverAndSubscribe(queueList string, checkQueueList bool, metaPrefix string) error {
 	var err error
+
+	discoveryDone = true
+
 	// What metrics can the queue manager provide?
 	if err == nil {
 		err = discoverStats(metaPrefix)

mqmetric/mqif.go

@@ -34,6 +34,7 @@ var (
 	qMgr             ibmmq.MQQueueManager
 	cmdQObj          ibmmq.MQObject
 	replyQObj        ibmmq.MQObject
+	replyQBaseName   string
 	statusReplyQObj  ibmmq.MQObject
 	getBuffer        = make([]byte, 32768)
 	platform         int32
@@ -133,9 +134,11 @@ func InitConnection(qMgrName string, replyQ string, cc *ConnectionConfig) error
 	if err == nil {
 		mqod := ibmmq.NewMQOD()
 		openOptions := ibmmq.MQOO_INPUT_AS_Q_DEF | ibmmq.MQOO_FAIL_IF_QUIESCING
+		openOptions |= ibmmq.MQOO_INQUIRE
 		mqod.ObjectType = ibmmq.MQOT_Q
 		mqod.ObjectName = replyQ
 		replyQObj, err = qMgr.Open(mqod, openOptions)
+		replyQBaseName = replyQ
 		if err == nil {
 			queuesOpened = true
 		}

samples/README.md

@@ -41,12 +41,16 @@ aspect.
 Apart from the `amqsconn.go` program, the other samples are designed to either connect
 to a local queue manager (on the same machine) or for the client configuration to be
 provided externally such as by the MQSERVER environment variable or the
-MQ Client Channel Definition Table (CCDT) file.
+MQ Client Channel Definition Table (CCDT) file. The MQ_CONNECT_TYPE environment
+variable can be used to force client connections to be made, even if you have
+installed the full server product; that variable is not needed if you have 
+only installed the MQ client libraries.
 
 For example
 
 ```
   export MQSERVER="SYSTEM.DEF.SVRCONN/TCP/localhost(1414)"
+  export MQ_CONNECT_TYPE=CLIENT  
   go run amqsput.go DEV.QUEUE.1 QM1
 ```