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request.go
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/
request.go
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// Copyright (c) 2018 Northwestern Mutual.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package grammes
import (
"context"
"github.com/google/uuid"
"github.com/northwesternmutual/grammes/gremconnect"
"github.com/northwesternmutual/grammes/gremerror"
"time"
)
var (
gremPrepareRequest = gremconnect.PrepareRequest
gremPackageRequest = gremconnect.PackageRequest
gremPrepareAuthRequest = gremconnect.PrepareAuthRequest
)
const (
clientTimeoutGrace = 20 * time.Second
)
func (c *Client) executeRequest(query string, queryTimeout *time.Duration, bindings, rebindings map[string]string, sessionId *uuid.UUID) ([][]byte, error) {
resolvedQueryTimeout := c.requestTimeout
if queryTimeout != nil {
resolvedQueryTimeout = *queryTimeout
}
err := c.requestSemaphore.Acquire(context.Background(), 1)
if err != nil {
c.logger.Error("acquiring request semaphore",
gremerror.NewGrammesError("executeRequest", err),
)
return nil, err
}
defer c.requestSemaphore.Release(1)
// Construct a map containing the values along
// with a randomly generated id to fetch the response.
req, id, err := gremPrepareRequest(query, &resolvedQueryTimeout, bindings, rebindings, sessionId)
if err != nil {
c.logger.Error("uuid generation when preparing request",
gremerror.NewGrammesError("executeRequest", err),
)
return nil, err
}
// Marshal the map and add on the
// mimetype to the header of the request.
msg, err := gremPackageRequest(req, c.gremlinVersion)
if err != nil {
c.logger.Error("unmarshal when packaging request",
gremerror.NewGrammesError("executeRequest", err),
)
return nil, err
}
c.resultMessenger.Store(id, make(chan int, 1))
c.dispatchRequest(msg) // send the request.
resp, err := c.retrieveResponse(id, resolvedQueryTimeout+clientTimeoutGrace) // retrieve the response from the gremlin server
if err != nil {
c.logger.Error("retrieving response",
gremerror.NewGrammesError("executeRequest", err),
)
return nil, err
}
return resp, nil
}
// writeWorker works on a loop and dispatches messages as soon as it receives them
func (c *Client) writeWorker(errs chan error, quit chan struct{}) {
for {
select {
// Wait for a response from the Request
// channel and store its value in a variable.
case msg := <-c.request:
// Write the message to the connection
// and check for any errors.
err := c.conn.Write(msg)
if err != nil {
errs <- err
c.broken = true
break
}
// Wait for a response from the quit
// channel and break out of the loop.
case <-quit:
return
}
}
}
func (c *Client) authenticate(requestID string) error {
auth, err := c.conn.Auth()
if err != nil {
return err
}
var req gremconnect.Request
if auth != nil {
req, err = gremPrepareAuthRequest(requestID, auth.Username, auth.Password)
if err != nil {
c.logger.Error("preparing authentication request",
gremerror.NewGrammesError("authenticate", err),
)
return err
}
c.logger.Debug("authenticate: Prepared authentication request", map[string]interface{}{})
}
// Marshal the map and add on the
// mimetype to the header of the request.
msg, err := gremPackageRequest(req, c.gremlinVersion)
if err != nil {
c.logger.Error("packaging request",
gremerror.NewGrammesError("authenticate", err),
)
return err
}
c.dispatchRequest(msg) // Send the request.
return nil
}
func (c *Client) dispatchRequest(msg []byte) {
c.logger.Debug("Dispatching request", map[string]interface{}{"request": string(msg)})
// Send the message through a channel
// for the writing worker to pickup and
// write to the connection.
c.request <- msg
}