mirror of
https://github.com/hyperledger/fabric-samples.git
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396 lines
13 KiB
Go
396 lines
13 KiB
Go
/*
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* Copyright IBM Corp All Rights Reserved
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Demonstrates how to handle data in an application with a high transaction volume where the transactions
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* all attempt to change the same key-value pair in the ledger. Such an application will have trouble
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* as multiple transactions may read a value at a certain version, which will then be invalid when the first
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* transaction updates the value to a new version, thus rejecting all other transactions until they're
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* re-executed.
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* Rather than relying on serialization of the transactions, which is slow, this application initializes
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* a value and then accepts deltas of that value which are added as rows to the ledger. The actual value
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* is then an aggregate of the initial value combined with all of the deltas. Additionally, a pruning
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* function is provided which aggregates and deletes the deltas to update the initial value. This should
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* be done during a maintenance window or when there is a lowered transaction volume, to avoid the proliferation
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* of millions of rows of data.
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*
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* @author Alexandre Pauwels for IBM
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* @created 17 Aug 2017
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*/
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package main
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/* Imports
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* 4 utility libraries for formatting, handling bytes, reading and writing JSON, and string manipulation
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* 2 specific Hyperledger Fabric specific libraries for Smart Contracts
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*/
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import (
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"fmt"
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"strconv"
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"github.com/hyperledger/fabric-chaincode-go/shim"
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pb "github.com/hyperledger/fabric-protos-go/peer"
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)
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//SmartContract is the data structure which represents this contract and on which various contract lifecycle functions are attached
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type SmartContract struct {
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}
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// Define Status codes for the response
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const (
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OK = 200
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ERROR = 500
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)
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// Init is called when the smart contract is instantiated
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func (s *SmartContract) Init(APIstub shim.ChaincodeStubInterface) pb.Response {
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return shim.Success(nil)
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}
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// Invoke routes invocations to the appropriate function in chaincode
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// Current supported invocations are:
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// - update, adds a delta to an aggregate variable in the ledger, all variables are assumed to start at 0
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// - get, retrieves the aggregate value of a variable in the ledger
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// - prune, deletes all rows associated with the variable and replaces them with a single row containing the aggregate value
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// - delete, removes all rows associated with the variable
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func (s *SmartContract) Invoke(APIstub shim.ChaincodeStubInterface) pb.Response {
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// Retrieve the requested Smart Contract function and arguments
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function, args := APIstub.GetFunctionAndParameters()
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// Route to the appropriate handler function to interact with the ledger appropriately
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if function == "update" {
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return s.update(APIstub, args)
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} else if function == "get" {
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return s.get(APIstub, args)
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} else if function == "prune" {
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return s.prune(APIstub, args)
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} else if function == "delete" {
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return s.delete(APIstub, args)
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} else if function == "putstandard" {
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return s.putStandard(APIstub, args)
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} else if function == "getstandard" {
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return s.getStandard(APIstub, args)
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} else if function == "delstandard" {
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return s.delStandard(APIstub, args)
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}
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return shim.Error("Invalid Smart Contract function name.")
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}
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/**
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* Updates the ledger to include a new delta for a particular variable. If this is the first time
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* this variable is being added to the ledger, then its initial value is assumed to be 0. The arguments
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* to give in the args array are as follows:
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* - args[0] -> name of the variable
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* - args[1] -> new delta (float)
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* - args[2] -> operation (currently supported are addition "+" and subtraction "-")
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*
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* @param APIstub The chaincode shim
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* @param args The arguments array for the update invocation
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*
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* @return A response structure indicating success or failure with a message
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*/
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func (s *SmartContract) update(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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// Check we have a valid number of args
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if len(args) != 3 {
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return shim.Error("Incorrect number of arguments, expecting 3")
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}
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// Extract the args
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name := args[0]
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op := args[2]
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_, err := strconv.ParseFloat(args[1], 64)
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if err != nil {
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return shim.Error("Provided value was not a number")
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}
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// Make sure a valid operator is provided
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if op != "+" && op != "-" {
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return shim.Error(fmt.Sprintf("Operator %s is unrecognized", op))
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}
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// Retrieve info needed for the update procedure
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txid := APIstub.GetTxID()
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compositeIndexName := "varName~op~value~txID"
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// Create the composite key that will allow us to query for all deltas on a particular variable
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compositeKey, compositeErr := APIstub.CreateCompositeKey(compositeIndexName, []string{name, op, args[1], txid})
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if compositeErr != nil {
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return shim.Error(fmt.Sprintf("Could not create a composite key for %s: %s", name, compositeErr.Error()))
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}
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// Save the composite key index
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compositePutErr := APIstub.PutState(compositeKey, []byte{0x00})
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if compositePutErr != nil {
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return shim.Error(fmt.Sprintf("Could not put operation for %s in the ledger: %s", name, compositePutErr.Error()))
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}
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return shim.Success([]byte(fmt.Sprintf("Successfully added %s%s to %s", op, args[1], name)))
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}
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/**
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* Retrieves the aggregate value of a variable in the ledger. Gets all delta rows for the variable
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* and computes the final value from all deltas. The args array for the invocation must contain the
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* following argument:
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* - args[0] -> The name of the variable to get the value of
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*
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* @param APIstub The chaincode shim
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* @param args The arguments array for the get invocation
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*
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* @return A response structure indicating success or failure with a message
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*/
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func (s *SmartContract) get(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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// Check we have a valid number of args
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if len(args) != 1 {
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return shim.Error("Incorrect number of arguments, expecting 1")
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}
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name := args[0]
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// Get all deltas for the variable
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deltaResultsIterator, deltaErr := APIstub.GetStateByPartialCompositeKey("varName~op~value~txID", []string{name})
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if deltaErr != nil {
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return shim.Error(fmt.Sprintf("Could not retrieve value for %s: %s", name, deltaErr.Error()))
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}
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defer deltaResultsIterator.Close()
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// Check the variable existed
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if !deltaResultsIterator.HasNext() {
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return shim.Error(fmt.Sprintf("No variable by the name %s exists", name))
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}
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// Iterate through result set and compute final value
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var finalVal float64
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var i int
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for i = 0; deltaResultsIterator.HasNext(); i++ {
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// Get the next row
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responseRange, nextErr := deltaResultsIterator.Next()
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if nextErr != nil {
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return shim.Error(nextErr.Error())
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}
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// Split the composite key into its component parts
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_, keyParts, splitKeyErr := APIstub.SplitCompositeKey(responseRange.Key)
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if splitKeyErr != nil {
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return shim.Error(splitKeyErr.Error())
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}
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// Retrieve the delta value and operation
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operation := keyParts[1]
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valueStr := keyParts[2]
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// Convert the value string and perform the operation
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value, convErr := strconv.ParseFloat(valueStr, 64)
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if convErr != nil {
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return shim.Error(convErr.Error())
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}
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switch operation {
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case "+":
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finalVal += value
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case "-":
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finalVal -= value
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default:
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return shim.Error(fmt.Sprintf("Unrecognized operation %s", operation))
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}
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}
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return shim.Success([]byte(strconv.FormatFloat(finalVal, 'f', -1, 64)))
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}
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/**
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* Prunes a variable by deleting all of its delta rows while computing the final value. Once all rows
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* have been processed and deleted, a single new row is added which defines a delta containing the final
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* computed value of the variable. The args array contains the following argument:
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* - args[0] -> The name of the variable to prune
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*
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* @param APIstub The chaincode shim
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* @param args The args array for the prune invocation
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*
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* @return A response structure indicating success or failure with a message
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*/
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func (s *SmartContract) prune(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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// Check we have a valid number of ars
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if len(args) != 1 {
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return shim.Error("Incorrect number of arguments, expecting 1")
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}
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// Retrieve the name of the variable to prune
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name := args[0]
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// Get all delta rows for the variable
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deltaResultsIterator, deltaErr := APIstub.GetStateByPartialCompositeKey("varName~op~value~txID", []string{name})
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if deltaErr != nil {
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return shim.Error(fmt.Sprintf("Could not retrieve value for %s: %s", name, deltaErr.Error()))
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}
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defer deltaResultsIterator.Close()
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// Check the variable existed
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if !deltaResultsIterator.HasNext() {
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return shim.Error(fmt.Sprintf("No variable by the name %s exists", name))
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}
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// Iterate through result set computing final value while iterating and deleting each key
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var finalVal float64
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var i int
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for i = 0; deltaResultsIterator.HasNext(); i++ {
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// Get the next row
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responseRange, nextErr := deltaResultsIterator.Next()
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if nextErr != nil {
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return shim.Error(nextErr.Error())
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}
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// Split the key into its composite parts
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_, keyParts, splitKeyErr := APIstub.SplitCompositeKey(responseRange.Key)
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if splitKeyErr != nil {
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return shim.Error(splitKeyErr.Error())
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}
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// Retrieve the operation and value
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operation := keyParts[1]
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valueStr := keyParts[2]
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// Convert the value to a float
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value, convErr := strconv.ParseFloat(valueStr, 64)
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if convErr != nil {
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return shim.Error(convErr.Error())
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}
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// Delete the row from the ledger
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deltaRowDelErr := APIstub.DelState(responseRange.Key)
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if deltaRowDelErr != nil {
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return shim.Error(fmt.Sprintf("Could not delete delta row: %s", deltaRowDelErr.Error()))
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}
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// Add the value of the deleted row to the final aggregate
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switch operation {
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case "+":
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finalVal += value
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case "-":
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finalVal -= value
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default:
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return shim.Error(fmt.Sprintf("Unrecognized operation %s", operation))
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}
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}
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// Update the ledger with the final value
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updateResp := s.update(APIstub, []string{name, strconv.FormatFloat(finalVal, 'f', -1, 64), "+"})
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if updateResp.Status == ERROR {
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return shim.Error(fmt.Sprintf("Could not update the final value of the variable after pruning: %s", updateResp.Message))
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}
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return shim.Success([]byte(fmt.Sprintf("Successfully pruned variable %s, final value is %f, %d rows pruned", args[0], finalVal, i)))
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}
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/**
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* Deletes all rows associated with an aggregate variable from the ledger. The args array
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* contains the following argument:
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* - args[0] -> The name of the variable to delete
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*
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* @param APIstub The chaincode shim
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* @param args The arguments array for the delete invocation
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*
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* @return A response structure indicating success or failure with a message
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*/
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func (s *SmartContract) delete(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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// Check there are a correct number of arguments
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if len(args) != 1 {
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return shim.Error("Incorrect number of arguments, expecting 1")
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}
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// Retrieve the variable name
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name := args[0]
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// Delete all delta rows
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deltaResultsIterator, deltaErr := APIstub.GetStateByPartialCompositeKey("varName~op~value~txID", []string{name})
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if deltaErr != nil {
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return shim.Error(fmt.Sprintf("Could not retrieve delta rows for %s: %s", name, deltaErr.Error()))
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}
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defer deltaResultsIterator.Close()
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// Ensure the variable exists
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if !deltaResultsIterator.HasNext() {
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return shim.Error(fmt.Sprintf("No variable by the name %s exists", name))
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}
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// Iterate through result set and delete all indices
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var i int
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for i = 0; deltaResultsIterator.HasNext(); i++ {
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responseRange, nextErr := deltaResultsIterator.Next()
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if nextErr != nil {
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return shim.Error(fmt.Sprintf("Could not retrieve next delta row: %s", nextErr.Error()))
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}
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deltaRowDelErr := APIstub.DelState(responseRange.Key)
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if deltaRowDelErr != nil {
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return shim.Error(fmt.Sprintf("Could not delete delta row: %s", deltaRowDelErr.Error()))
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}
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}
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return shim.Success([]byte(fmt.Sprintf("Deleted %s, %d rows removed", name, i)))
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}
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/**
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* Converts a float64 to a byte array
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*
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* @param f The float64 to convert
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*
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* @return The byte array representation
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*/
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func f2barr(f float64) []byte {
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str := strconv.FormatFloat(f, 'f', -1, 64)
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return []byte(str)
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}
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// The main function is only relevant in unit test mode. Only included here for completeness.
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func main() {
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// Create a new Smart Contract
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err := shim.Start(new(SmartContract))
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if err != nil {
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fmt.Printf("Error creating new Smart Contract: %s", err)
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}
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}
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/**
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* All functions below this are for testing traditional editing of a single row
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*/
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func (s *SmartContract) putStandard(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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name := args[0]
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valStr := args[1]
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_, getErr := APIstub.GetState(name)
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if getErr != nil {
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return shim.Error(fmt.Sprintf("Failed to retrieve the state of %s: %s", name, getErr.Error()))
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}
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putErr := APIstub.PutState(name, []byte(valStr))
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if putErr != nil {
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return shim.Error(fmt.Sprintf("Failed to put state: %s", putErr.Error()))
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}
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return shim.Success(nil)
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}
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func (s *SmartContract) getStandard(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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name := args[0]
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val, getErr := APIstub.GetState(name)
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if getErr != nil {
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return shim.Error(fmt.Sprintf("Failed to get state: %s", getErr.Error()))
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}
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return shim.Success(val)
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}
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func (s *SmartContract) delStandard(APIstub shim.ChaincodeStubInterface, args []string) pb.Response {
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name := args[0]
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getErr := APIstub.DelState(name)
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if getErr != nil {
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return shim.Error(fmt.Sprintf("Failed to delete state: %s", getErr.Error()))
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}
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return shim.Success(nil)
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}
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