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ctrl/requests_copy.go

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package steward
import (
"context"
"fmt"
"log"
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"github.com/google/uuid"
)
type methodREQCopySrc struct {
event Event
}
func (m methodREQCopySrc) getKind() Event {
return m.event
}
// Idea:
//
// Initialization, Source:
// - Use the REQCopySrc method to handle the initial request from the user.
// - Spawn a REQCopySrc_uid subscriber to receive sync messages from destination.
// - Send the uid, and full-file hash to the destination in a REQCopyDst message.
//
// Initialization, Destination:
// - Spawn a REQCopyDst-uid from the uid we got from source.
// --------------------------------------------------------------------------------------
//
// All below happens in the From-uid and To-uid methods until the copying is done.
//
// - dst->src, dst sends a REQCopySrc-uid message with status "ready" file receiving to src.
// - src receives the message and start reading the file:
// - src, creates hash of the complete file.
// - src, reads the file in chunks, and create a hash of each chunk.
// - src->dst, send chunk when read.
// - dst->src, wait for status "ready" indicating the chuck was transfered.
// - Loop and read new chunc.
// - src->dst, when last chunch is sent send status "last"
// - src->dst, if failure send status "error", abort file copying and clean up on both src and dst.
//
// - dst, read and store each chunch to tmp folder and verify hash.
// - dst->src, send status "ready" to src when chunch is stored.
// - loop and check for status "last", if last:
// - build original file from chuncs.
// - verify hash when file is built.
// - dst->src, send status "done".
//
// - We should also be be able to resend a chunk, or restart the copying from where we left of if it seems to hang.
//
// dataStructure{
// Data []bytes
// Status copyStatus
// id int
// }
//
// Create a new copy sync process to handle the actual file copying.
// We use the context already created based on the time out specified
// in the requestTimeout field of the message.
//
// -----------------------------------------------------
// Handle writing to a file. Will truncate any existing data if the file did already
// exist.
func (m methodREQCopySrc) handler(proc process, message Message, node string) ([]byte, error) {
var subProcessName string
proc.processes.wg.Add(1)
go func() {
defer proc.processes.wg.Done()
switch {
case len(message.MethodArgs) < 3:
er := fmt.Errorf("error: methodREQCopySrc: got <3 number methodArgs: want srcfilePath,dstNode,dstFilePath")
proc.errorKernel.errSend(proc, message, er)
return
}
// SrcFilePath := message.MethodArgs[0]
// DstNode := message.MethodArgs[1]
// DstFilePath := message.MethodArgs[2]
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// Get a context with the timeout specified in message.MethodTimeout.
// Since the subProc spawned will outlive this method here we do not
// want to cancel this method. We care about the methodTimeout, but
// we ignore the CancelFunc.
ctx, _ := getContextForMethodTimeout(proc.ctx, message)
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// Create a subject for one copy request
uid := uuid.New()
subProcessName = fmt.Sprintf("copySrc_%v", uid.String())
m := Method(subProcessName)
sub := newSubjectNoVerifyHandler(m, node)
// Create a new sub process that will do the actual file copying.
copySrcSubProc := newProcess(ctx, proc.server, sub, processKindSubscriber, nil)
// Give the sub process a procFunc so we do the actual copying within a procFunc,
// and not directly within the handler.
copySrcSubProc.procFunc = copySrcProcFunc(copySrcSubProc)
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// The process will be killed when the context expires.
go copySrcSubProc.spawnWorker()
//replyData := fmt.Sprintf("info: succesfully initiated copy: srcNode=%v, srcPath=%v, dstNode=%v, dstPath=%v, starting sub process=%v for the actual copying\n", node, SrcFilePath, DstNode, DstFilePath, subProcessName)
//
//newReplyMessage(proc, message, []byte(replyData))
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}()
ackMsg := []byte("confirmed from: " + node + ": " + fmt.Sprint(message.ID))
return ackMsg, nil
}
func copySrcProcFunc(proc process) func(context.Context, chan Message) error {
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pf := func(ctx context.Context, procFuncCh chan Message) error {
select {
case <-ctx.Done():
log.Printf(" * copySrcProcFunc ended: %v\n", proc.processName)
}
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return nil
}
return pf
}
// ----
type methodREQCopyDst struct {
event Event
}
func (m methodREQCopyDst) getKind() Event {
return m.event
}
// Handle writing to a file. Will truncate any existing data if the file did already
// exist.
// Same as the REQToFile, but this requst type don't use the default data folder path
// for where to store files or add information about node names.
// This method also sends a msgReply back to the publisher if the method was done
// successfully, where REQToFile do not.
// This method will truncate and overwrite any existing files.
func (m methodREQCopyDst) handler(proc process, message Message, node string) ([]byte, error) {
proc.processes.wg.Add(1)
go func() {
defer proc.processes.wg.Done()
}()
ackMsg := []byte("confirmed from: " + node + ": " + fmt.Sprint(message.ID))
return ackMsg, nil
}