Diff: MQTT/MQTTAsync.h

Revision:

43:dcde0e66874a

Parent:

11:3802c82a5ae9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MQTT/MQTTAsync.h	Thu Mar 08 13:13:53 2018 +0000
@@ -0,0 +1,607 @@
+/*******************************************************************************
+ * Copyright (c) 2014 IBM Corp.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ *
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at
+ *   http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * Contributors:
+ *    Ian Craggs - initial API and implementation and/or initial documentation
+ *******************************************************************************/
+
+#if !defined(MQTTASYNC_H)
+#define MQTTASYNC_H
+
+#include "FP.h"
+#include "MQTTPacket.h"
+#include "stdio.h"
+
+namespace MQTT
+{
+
+
+enum QoS { QOS0, QOS1, QOS2 };
+
+
+struct Message
+{
+    enum QoS qos;
+    bool retained;
+    bool dup;
+    unsigned short id;
+    void *payload;
+    size_t payloadlen;
+};
+
+
+class PacketId
+{
+public:
+    PacketId();
+    
+    int getNext();
+   
+private:
+    static const int MAX_PACKET_ID = 65535;
+    int next;
+};
+
+typedef void (*messageHandler)(Message*);
+
+typedef struct limits
+{
+	int MAX_MQTT_PACKET_SIZE; // 
+	int MAX_MESSAGE_HANDLERS;  // each subscription requires a message handler
+	int MAX_CONCURRENT_OPERATIONS;  // each command which runs concurrently can have a result handler, when we are in multi-threaded mode
+	int command_timeout_ms;
+		
+	limits()
+	{
+		MAX_MQTT_PACKET_SIZE = 100;
+		MAX_MESSAGE_HANDLERS = 5;
+		MAX_CONCURRENT_OPERATIONS = 1; // 1 indicates single-threaded mode - set to >1 for multithreaded mode
+		command_timeout_ms = 30000;
+	}
+} Limits;
+  
+
+/**
+ * @class Async
+ * @brief non-blocking, threaded MQTT client API
+ * @param Network a network class which supports send, receive
+ * @param Timer a timer class with the methods: 
+ */ 
+template<class Network, class Timer, class Thread, class Mutex> class Async
+{
+    
+public:    
+
+	struct Result
+	{
+    	/* success or failure result data */
+    	Async<Network, Timer, Thread, Mutex>* client;
+		int rc;
+	};
+
+	typedef void (*resultHandler)(Result*);	
+   
+    Async(Network* network, const Limits limits = Limits()); 
+        
+    typedef struct
+    {
+        Async* client;
+        Network* network;
+    } connectionLostInfo;
+    
+    typedef int (*connectionLostHandlers)(connectionLostInfo*);
+    
+    /** Set the connection lost callback - called whenever the connection is lost and we should be connected
+     *  @param clh - pointer to the callback function
+     */
+    void setConnectionLostHandler(connectionLostHandlers clh)
+    {
+        connectionLostHandler.attach(clh);
+    }
+    
+    /** Set the default message handling callback - used for any message which does not match a subscription message handler
+     *  @param mh - pointer to the callback function
+     */
+    void setDefaultMessageHandler(messageHandler mh)
+    {
+        defaultMessageHandler.attach(mh);
+    }
+           
+    int connect(resultHandler fn, MQTTPacket_connectData* options = 0);
+    
+     template<class T>
+    int connect(void(T::*method)(Result *), MQTTPacket_connectData* options = 0, T *item = 0);  // alternative to pass in pointer to member function
+        
+    int publish(resultHandler rh, const char* topic, Message* message);
+    
+    int subscribe(resultHandler rh, const char* topicFilter, enum QoS qos, messageHandler mh);
+    
+    int unsubscribe(resultHandler rh, const char* topicFilter);
+    
+    int disconnect(resultHandler rh);
+    
+private:
+
+    void run(void const *argument);
+    int cycle(int timeout);
+    int waitfor(int packet_type, Timer& atimer);
+	int keepalive();
+	int findFreeOperation();
+
+    int decodePacket(int* value, int timeout);
+    int readPacket(int timeout);
+    int sendPacket(int length, int timeout);
+	int deliverMessage(MQTTString* topic, Message* message);
+    
+    Thread* thread;
+    Network* ipstack;
+    
+    Limits limits;
+    
+    char* buf;  
+    char* readbuf;
+
+    Timer ping_timer, connect_timer;
+    unsigned int keepAliveInterval;
+	bool ping_outstanding;
+    
+    PacketId packetid;
+    
+    typedef FP<void, Result*> resultHandlerFP;    
+    resultHandlerFP connectHandler; 
+    
+    typedef FP<void, Message*> messageHandlerFP;
+    struct MessageHandlers
+    {
+    	const char* topic;
+    	messageHandlerFP fp;
+    } *messageHandlers;      // Message handlers are indexed by subscription topic
+    
+    // how many concurrent operations should we allow?  Each one will require a function pointer
+    struct Operations
+    {
+    	unsigned short id;
+    	resultHandlerFP fp;
+    	const char* topic;         // if this is a publish, store topic name in case republishing is required
+    	Message* message;    // for publish, 
+    	Timer timer;         // to check if the command has timed out
+    } *operations;           // result handlers are indexed by packet ids
+
+	static void threadfn(void* arg);
+	
+	messageHandlerFP defaultMessageHandler;
+    
+    typedef FP<int, connectionLostInfo*> connectionLostFP;
+    
+    connectionLostFP connectionLostHandler;
+    
+};
+
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> void MQTT::Async<Network, Timer, Thread, Mutex>::threadfn(void* arg)
+{
+    ((Async<Network, Timer, Thread, Mutex>*) arg)->run(NULL);
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> MQTT::Async<Network, Timer, Thread, Mutex>::Async(Network* network, Limits limits)  : limits(limits), packetid()
+{
+	this->thread = 0;
+	this->ipstack = network;
+	this->ping_timer = Timer();
+	this->ping_outstanding = 0;
+	   
+	// How to make these memory allocations portable?  I was hoping to avoid the heap
+	buf = new char[limits.MAX_MQTT_PACKET_SIZE];
+	readbuf = new char[limits.MAX_MQTT_PACKET_SIZE];
+	this->operations = new struct Operations[limits.MAX_CONCURRENT_OPERATIONS];
+	for (int i = 0; i < limits.MAX_CONCURRENT_OPERATIONS; ++i)
+		operations[i].id = 0;
+	this->messageHandlers = new struct MessageHandlers[limits.MAX_MESSAGE_HANDLERS];
+	for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i)
+		messageHandlers[i].topic = 0;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::sendPacket(int length, int timeout)
+{
+    int sent = 0;
+    
+    while (sent < length)
+        sent += ipstack->write(&buf[sent], length, timeout);
+	if (sent == length)
+	    ping_timer.countdown(this->keepAliveInterval); // record the fact that we have successfully sent the packet    
+    return sent;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::decodePacket(int* value, int timeout)
+{
+    char c;
+    int multiplier = 1;
+    int len = 0;
+	const int MAX_NO_OF_REMAINING_LENGTH_BYTES = 4;
+
+    *value = 0;
+    do
+    {
+        int rc = MQTTPACKET_READ_ERROR;
+
+        if (++len > MAX_NO_OF_REMAINING_LENGTH_BYTES)
+        {
+            rc = MQTTPACKET_READ_ERROR; /* bad data */
+            goto exit;
+        }
+        rc = ipstack->read(&c, 1, timeout);
+        if (rc != 1)
+            goto exit;
+        *value += (c & 127) * multiplier;
+        multiplier *= 128;
+    } while ((c & 128) != 0);
+exit:
+    return len;
+}
+
+
+/**
+ * If any read fails in this method, then we should disconnect from the network, as on reconnect
+ * the packets can be retried. 
+ * @param timeout the max time to wait for the packet read to complete, in milliseconds
+ * @return the MQTT packet type, or -1 if none
+ */
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::readPacket(int timeout) 
+{
+    int rc = -1;
+    MQTTHeader header = {0};
+    int len = 0;
+    int rem_len = 0;
+
+    /* 1. read the header byte.  This has the packet type in it */
+    if (ipstack->read(readbuf, 1, timeout) != 1)
+        goto exit;
+
+    len = 1;
+    /* 2. read the remaining length.  This is variable in itself */
+    decodePacket(&rem_len, timeout);
+    len += MQTTPacket_encode(readbuf + 1, rem_len); /* put the original remaining length back into the buffer */
+
+    /* 3. read the rest of the buffer using a callback to supply the rest of the data */
+    if (ipstack->read(readbuf + len, rem_len, timeout) != rem_len)
+        goto exit;
+
+    header.byte = readbuf[0];
+    rc = header.bits.type;
+exit:
+    return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::deliverMessage(MQTTString* topic, Message* message)
+{
+	int rc = -1;
+
+	// we have to find the right message handler - indexed by topic
+	for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i)
+	{
+		if (messageHandlers[i].topic != 0 && MQTTPacket_equals(topic, (char*)messageHandlers[i].topic))
+		{
+			messageHandlers[i].fp(message);
+			rc = 0;
+			break;
+		}
+	}
+	
+	return rc;
+}
+
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::cycle(int timeout)
+{
+    /* get one piece of work off the wire and one pass through */
+
+    // read the socket, see what work is due
+    int packet_type = readPacket(timeout);
+    
+	int len, rc;
+    switch (packet_type)
+    {
+        case CONNACK:
+			if (this->thread)
+			{
+				Result res = {this, 0};
+            	if (MQTTDeserialize_connack(&res.rc, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+                	;
+				connectHandler(&res);
+				connectHandler.detach(); // only invoke the callback once
+			}
+			break;
+        case PUBACK:
+        	if (this->thread)
+        		; //call resultHandler
+        case SUBACK:
+            break;
+        case PUBLISH:
+			MQTTString topicName;
+			Message msg;
+			rc = MQTTDeserialize_publish((int*)&msg.dup, (int*)&msg.qos, (int*)&msg.retained, (int*)&msg.id, &topicName,
+								 (char**)&msg.payload, (int*)&msg.payloadlen, readbuf, limits.MAX_MQTT_PACKET_SIZE);;
+			if (msg.qos == QOS0)
+				deliverMessage(&topicName, &msg);
+            break;
+        case PUBREC:
+   	        int type, dup, mypacketid;
+   	        if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+   	            ; 
+   	        // must lock this access against the application thread, if we are multi-threaded
+			len = MQTTSerialize_ack(buf, limits.MAX_MQTT_PACKET_SIZE, PUBREL, 0, mypacketid);
+		    rc = sendPacket(len, timeout); // send the PUBREL packet
+			if (rc != len) 
+				goto exit; // there was a problem
+
+            break;
+        case PUBCOMP:
+            break;
+        case PINGRESP:
+			ping_outstanding = false;
+            break;
+    }
+	keepalive();
+exit:
+    return packet_type;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::keepalive()
+{
+	int rc = 0;
+
+	if (keepAliveInterval == 0)
+		goto exit;
+
+	if (ping_timer.expired())
+	{
+		if (ping_outstanding)
+			rc = -1;
+		else
+		{
+			int len = MQTTSerialize_pingreq(buf, limits.MAX_MQTT_PACKET_SIZE);
+			rc = sendPacket(len, 1000); // send the ping packet
+			if (rc != len) 
+				rc = -1; // indicate there's a problem
+			else
+				ping_outstanding = true;
+		}
+	}
+
+exit:
+	return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> void MQTT::Async<Network, Timer, Thread, Mutex>::run(void const *argument)
+{
+	while (true)
+		cycle(ping_timer.left_ms());
+}
+
+
+// only used in single-threaded mode where one command at a time is in process
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::waitfor(int packet_type, Timer& atimer)
+{
+	int rc = -1;
+	
+	do
+    {
+		if (atimer.expired()) 
+			break; // we timed out
+	}
+	while ((rc = cycle(atimer.left_ms())) != packet_type);	
+	
+	return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::connect(resultHandler resultHandler, MQTTPacket_connectData* options)
+{
+	connect_timer.countdown(limits.command_timeout_ms);
+
+    MQTTPacket_connectData default_options = MQTTPacket_connectData_initializer;
+    if (options == 0)
+        options = &default_options; // set default options if none were supplied
+    
+    this->keepAliveInterval = options->keepAliveInterval;
+	ping_timer.countdown(this->keepAliveInterval);
+    int len = MQTTSerialize_connect(buf, limits.MAX_MQTT_PACKET_SIZE, options);
+    int rc = sendPacket(len, connect_timer.left_ms()); // send the connect packet
+	if (rc != len) 
+		goto exit; // there was a problem
+    
+    if (resultHandler == 0)     // wait until the connack is received 
+    {
+        // this will be a blocking call, wait for the connack
+		if (waitfor(CONNACK, connect_timer) == CONNACK)
+		{
+        	int connack_rc = -1;
+        	if (MQTTDeserialize_connack(&connack_rc, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+	        	rc = connack_rc;
+	    }
+    }
+    else
+    {
+        // set connect response callback function
+        connectHandler.attach(resultHandler);
+        
+        // start background thread            
+        this->thread = new Thread((void (*)(void const *argument))&MQTT::Async<Network, Timer, Thread, Mutex>::threadfn, (void*)this);
+    }
+    
+exit:
+    return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::findFreeOperation()
+{
+	int found = -1;
+	for (int i = 0; i < limits.MAX_CONCURRENT_OPERATIONS; ++i)
+	{
+		if (operations[i].id == 0)
+		{
+			found = i;
+			break;
+		}
+	}
+	return found;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::subscribe(resultHandler resultHandler, const char* topicFilter, enum QoS qos, messageHandler messageHandler)
+{
+	int index = 0;
+	if (this->thread)
+		index = findFreeOperation();	
+	Timer& atimer = operations[index].timer;
+	
+	atimer.countdown(limits.command_timeout_ms);
+    MQTTString topic = {(char*)topicFilter, 0, 0};
+    
+    int len = MQTTSerialize_subscribe(buf, limits.MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic, (int*)&qos);
+    int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet
+	if (rc != len) 
+		goto exit; // there was a problem
+    
+    /* wait for suback */
+    if (resultHandler == 0)
+    {
+        // this will block
+        if (waitfor(SUBACK, atimer) == SUBACK)
+        {
+            int count = 0, grantedQoS = -1, mypacketid;
+            if (MQTTDeserialize_suback(&mypacketid, 1, &count, &grantedQoS, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+                rc = grantedQoS; // 0, 1, 2 or 0x80 
+            if (rc != 0x80)
+            {
+            	for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i)
+				{
+					if (messageHandlers[i].topic == 0)
+					{
+						messageHandlers[i].topic = topicFilter;
+						messageHandlers[i].fp.attach(messageHandler);
+						rc = 0;
+						break;
+					}
+				}
+            }
+        }
+    }
+    else
+    {
+        // set subscribe response callback function
+        
+    }
+    
+exit:
+    return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::unsubscribe(resultHandler resultHandler, const char* topicFilter)
+{
+	int index = 0;
+	if (this->thread)
+		index = findFreeOperation();	
+	Timer& atimer = operations[index].timer;
+
+	atimer.countdown(limits.command_timeout_ms);
+    MQTTString topic = {(char*)topicFilter, 0, 0};
+    
+    int len = MQTTSerialize_unsubscribe(buf, limits.MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic);
+    int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet
+	if (rc != len) 
+		goto exit; // there was a problem
+    
+    // set unsubscribe response callback function
+        
+    
+exit:
+    return rc;
+}
+
+
+   
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::publish(resultHandler resultHandler, const char* topicName, Message* message)
+{
+	int index = 0;
+	if (this->thread)
+		index = findFreeOperation();	
+	Timer& atimer = operations[index].timer;
+
+	atimer.countdown(limits.command_timeout_ms);
+    MQTTString topic = {(char*)topicName, 0, 0};
+
+	if (message->qos == QOS1 || message->qos == QOS2)
+		message->id = packetid.getNext();
+    
+	int len = MQTTSerialize_publish(buf, limits.MAX_MQTT_PACKET_SIZE, 0, message->qos, message->retained, message->id, topic, (char*)message->payload, message->payloadlen);
+    int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet
+	if (rc != len) 
+		goto exit; // there was a problem
+    
+    /* wait for acks */
+    if (resultHandler == 0)
+    {
+ 		if (message->qos == QOS1)
+		{
+	        if (waitfor(PUBACK, atimer) == PUBACK)
+    	    {
+    	        int type, dup, mypacketid;
+    	        if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+    	            rc = 0; 
+    	    }
+		}
+		else if (message->qos == QOS2)
+		{
+	        if (waitfor(PUBCOMP, atimer) == PUBCOMP)
+	   	    {
+	   	    	int type, dup, mypacketid;
+            	if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1)
+    	           	rc = 0; 
+			}
+
+		}
+    }
+    else
+    {
+        // set publish response callback function
+        
+    }
+    
+exit:
+    return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Async<Network, Timer, Thread, Mutex>::disconnect(resultHandler resultHandler)
+{  
+    Timer timer = Timer(limits.command_timeout_ms);     // we might wait for incomplete incoming publishes to complete
+    int len = MQTTSerialize_disconnect(buf, limits.MAX_MQTT_PACKET_SIZE);
+    int rc = sendPacket(len, timer.left_ms());   // send the disconnect packet
+    
+    return (rc == len) ? 0 : -1;
+}
+
+
+
+#endif
\ No newline at end of file