| # |
| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You under the Apache License, Version 2.0 |
| # (the "License"); you may not use this file except in compliance with |
| # the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| # |
| |
| # S4 class representing Broadcast variables |
| |
| # Hidden environment that holds values for broadcast variables |
| # This will not be serialized / shipped by default |
| .broadcastNames <- new.env() |
| .broadcastValues <- new.env() |
| .broadcastIdToName <- new.env() |
| |
| # S4 class that represents a Broadcast variable |
| # |
| # Broadcast variables can be created using the broadcast |
| # function from a \code{SparkContext}. |
| # |
| # @rdname broadcast-class |
| # @seealso broadcast |
| # |
| # @param id Id of the backing Spark broadcast variable |
| setClass("Broadcast", slots = list(id = "character")) |
| |
| # @rdname broadcast-class |
| # @param value Value of the broadcast variable |
| # @param jBroadcastRef reference to the backing Java broadcast object |
| # @param objName name of broadcasted object |
| Broadcast <- function(id, value, jBroadcastRef, objName) { |
| .broadcastValues[[id]] <- value |
| .broadcastNames[[as.character(objName)]] <- jBroadcastRef |
| .broadcastIdToName[[id]] <- as.character(objName) |
| new("Broadcast", id = id) |
| } |
| |
| # @description |
| # \code{value} can be used to get the value of a broadcast variable inside |
| # a distributed function. |
| # |
| # @param bcast The broadcast variable to get |
| # @rdname broadcast |
| setMethod("value", |
| signature(bcast = "Broadcast"), |
| function(bcast) { |
| if (exists(bcast@id, envir = .broadcastValues)) { |
| get(bcast@id, envir = .broadcastValues) |
| } else { |
| NULL |
| } |
| }) |
| |
| # Internal function to set values of a broadcast variable. |
| # |
| # This function is used internally by Spark to set the value of a broadcast |
| # variable on workers. Not intended for use outside the package. |
| # |
| # @rdname broadcast-internal |
| # @seealso broadcast, value |
| |
| # @param bcastId The id of broadcast variable to set |
| # @param value The value to be set |
| setBroadcastValue <- function(bcastId, value) { |
| bcastIdStr <- as.character(bcastId) |
| .broadcastValues[[bcastIdStr]] <- value |
| } |
| |
| # Helper function to clear the list of broadcast variables we know about |
| # Should be called when the SparkR JVM backend is shutdown |
| clearBroadcastVariables <- function() { |
| bcasts <- ls(.broadcastNames) |
| rm(list = bcasts, envir = .broadcastNames) |
| } |