Assignment functionality addition

kfk.c

@@ -723,6 +723,126 @@ EXP K3(kfkPoll){
   return kj(n);
 }
 
+
+/* The following set of functions define interactions with the assign functionality with Kafka.
+ * This provides more control to the user over where data can be consumed from.
+ * Note the differences between Kafka Assign vs Subscribe functionality, summarised in part
+ * https://github.com/confluentinc/confluent-kafka-dotnet/issues/278#issuecomment-318858243
+*/
+
+/** Define functionality needed for the addition and deletion of topic-partition 
+ ** pairs to the current assignment
+ * @param dict topic!associated-partitions --> S!J
+*/
+
+static V ptlistadd(K dict, rd_kafka_topic_partition_list_t *t_partition){
+  K dk=kK(dict)[0],dv=kK(dict)[1];
+  S*p;J*o,i;
+  p=kS(dk);o=kJ(dv);
+  for(i = 0; i < dk->n; i++)
+    rd_kafka_topic_partition_list_add(t_partition,p[i],o[i]);
+}
+
+static V ptlistdel(K dict,rd_kafka_topic_partition_list_t *t_partition){
+  K dk=kK(dict)[0],dv=kK(dict)[1];
+  S*p;J*o,i;
+  p=kS(dk);o=kJ(dv);
+  for(i = 0; i < dk->n; i++)
+    rd_kafka_topic_partition_list_del(t_partition,p[i],o[i]);
+}
+
+/** Assign the partitions from which to consume data for specified topics
+ * @param x Client Index (previously created)
+ * @param y Dictionary mapping individual topics to associated partitions. S!J
+ * @returns Null value on correct execution
+*/
+
+EXP K2(kfkAssignTopPar){
+  rd_kafka_t *rk;
+  rd_kafka_topic_partition_list_t *t_partition;
+  rd_kafka_resp_err_t err;
+  if(!checkType("i", x))
+    return KNL;
+  if(!(rk= clientIndex(x)))
+    return KNL;
+  t_partition = rd_kafka_topic_partition_list_new(y->n);
+  // topic-partition assignment
+  ptlistadd(y,t_partition);
+  if(KFK_OK != (err=rd_kafka_assign(rk,t_partition)))
+    return krr((S) rd_kafka_err2str(err));
+  rd_kafka_topic_partition_list_destroy(t_partition);
+  return KNL;
+}
+
+/** Return the current consumption assignment for a specified client
+ * @param x Client Index (previously created) 
+ * @returns List of dictionaries defining information about the current assignment
+*/
+EXP K1(kfkAssignment){
+  K r;
+  rd_kafka_topic_partition_list_t *t;
+  rd_kafka_t *rk;
+  rd_kafka_resp_err_t err;
+  if(!checkType("i", x))
+    return KNL;
+  if(!(rk= clientIndex(x)))
+    return KNL;
+  if(KFK_OK != (err=rd_kafka_assignment(rk, &t)))
+    return krr((S)rd_kafka_err2str(err));
+  r = decodeParList(t);
+  rd_kafka_topic_partition_list_destroy(t);
+  return r;
+}
+
+/** Add to the current assignment for a client with new topic-partition pair
+ * @param x Client Index (previously created)
+ * @param y Dictionary mapping individual topics to associated partitions. S!J
+ * @returns Null value on correct execution
+*/
+
+EXP K2(kfkAssignmentAdd){
+  rd_kafka_t *rk;
+  rd_kafka_topic_partition_list_t *t;
+  rd_kafka_resp_err_t err;
+  if(!checkType("i", x))
+    return KNL;
+  if(!(rk= clientIndex(x)))
+    return KNL;
+  // retrieve the current assignment
+  if(KFK_OK != (err=rd_kafka_assignment(rk, &t)))
+    return krr((S)rd_kafka_err2str(err));
+  ptlistadd(y,t);
+  if(KFK_OK != (err=rd_kafka_assign(rk,t)))
+    return krr((S) rd_kafka_err2str(err));
+  rd_kafka_topic_partition_list_destroy(t);
+  return 0;
+}
+
+/** Delete a topic-partition mapped dictionary from the current assignment for a client
+ * @param x Client Index (previously created)
+ * @param y Dictionary mapping individual topics to associated partitions. S!J
+ * @returns Null value on correct execution
+*/
+
+EXP K2(kfkAssignmentDel){
+  rd_kafka_t *rk;
+  rd_kafka_topic_partition_list_t *t;
+  rd_kafka_resp_err_t err;
+  if(!checkType("i", x))
+    return KNL;
+  if(!(rk= clientIndex(x)))
+    return KNL;
+  // retrieve the current assignment
+  if(KFK_OK != (err=rd_kafka_assignment(rk, &t)))
+    return krr((S)rd_kafka_err2str(err));
+  ptlistdel(y,t);
+  if(KFK_OK != (err=rd_kafka_assign(rk,t)))
+    return krr((S) rd_kafka_err2str(err));
+  rd_kafka_topic_partition_list_destroy(t);
+  return 0;
+}
+
+
 // other
 EXP K1(kfkOutQLen){
   rd_kafka_t *rk;

kfk.q

@@ -56,7 +56,15 @@ funcs:(
           // .kfk.VersionSym[]:s
         (`kfkVersionSym;1);
           // .kfk.SetLoggerLevel[client_id:i;int_level:i]:()
-        (`kfkSetLoggerLevel;2)
+        (`kfkSetLoggerLevel;2);
+          // .kfk.Assignment[client_id:i]:T
+        (`kfkAssignment;1);
+          // .kfk.AssignTopPar[client_id:i;topic_partition:S!J]:()
+        (`kfkAssignTopPar;2);
+          // .kfk.AssignmentAdd[client_id:i;topic_partition:S!J]:()
+        (`kfkAssignmentAdd;2);
+          // .kfk.AssignmentDel[client_id:i;topic_partition:S!J]:()
+        (`kfkAssignmentDel;2)
 	);
 
 // binding functions from dictionary funcs using rule
@@ -156,6 +164,71 @@ Subscribe:{[cid;top;part;cb]
   }
 
 
+// Assignment API logic
+
+// Assign a new topic-partition dictionary to be consumed by a designated clientid
+/* cid    = Integer denoting client ID
+/* toppar = Symbol!Long dictionary mapping the name of a topic to an associated partition
+Assign:{[cid;toppar]
+  i.checkDict[toppar];
+  // Create a distinct set of topic-partition pairs to assign,
+  // non distinct entries cause a segfault
+  toppar:(!). flip distinct(,'/)(key;value)@\:toppar;
+  AssignTopPar[cid;toppar]
+  }
+
+// Assign additional topic-partition pairs which could be consumed from
+/* cid    = Integer denoting client ID
+/* toppar = Symbol!Long dictionary mapping the name of a topic to an associated partition
+AssignAdd:{[cid;toppar]
+  tpdict:i.assignCheck[cid;toppar;0b];
+  AssignmentAdd[cid;tpdict];
+  }
+
+// Remove assigned topic-parition pairs from the current assignment from which data can be consumed
+/* cid    = Integer denoting client ID
+/* toppar = Symbol!Long dictionary mapping the name of a topic to an associated partition
+AssignDel:{[cid;toppar]
+  tpdict:i.assignCheck[cid;toppar;1b];
+  AssignmentDel[cid;tpdict];
+  }
+
+// Utility function to check current assignment against proposed additions/deletions,
+// retirn unique toppar pairs as a dictionary to avoid segfaults from duplicate 
+/* cid    = Integer denoting the client ID
+/* toppar = Symbol!Long dictionary mapping the name of a topic to an associated partition
+/* addDel = Boolean denoting addition/deletion functionality
+i.assignCheck:{[cid;toppar;addDel]
+  i.checkDict[toppar];
+  // Generate the partition provided used to compare to current assignment
+  tplist:distinct(,'/)(key;value)@\:toppar;
+  // Mark locations where user is attempting to delete from an non existent assignment
+  loc:$[addDel;not;]i.compAssign[cid;tplist];
+  if[any loc;
+    show tplist where loc;
+    $[addDel;
+      '"The above topic-partition pairs cannot be deleted as they are not assigned";
+      '"The above topic-partition pairs already exist, please modify dictionary"]
+    ];
+  (!). flip tplist
+  }
+
+// dictionary defining the current assignment for used in comparisons 
+i.compAssign:{[cid;tplist]
+  assignment:Assignment[cid];
+  // current assignment is a list of dictionaries
+  currentTopPar:(assignment@'`topic),'"j"$assignment@'`partition;
+  tplist in currentTopPar
+  }
+
+// Ensure that the dictionaries used in assignments map symbol to long
+i.checkDict:{[dict]
+  if[not 99h=type dict      ;'"Final parameter must be a dictionary"];
+  if[not 11h=type key dict  ;'"Dictionary key must of type symbol"];
+  if[not 7h =type value dict;'"Dictionary values must be of type long"];
+  }
+
+
 // Handling of error callbacks (rd_kafka_conf_set_error_cb)
 /* cid is an integer
 /* err_int is an integer code relating to the kafka issue