scale_delay.go

Documentation: scheduler/api/api_monitoring

     1  /*
     2   * P2PFaaS - A framework for FaaS Load Balancing
     3   * Copyright (c) 2019 - 2022. Gabriele Proietti Mattia <pm.gabriele@outlook.com>
     4   *
     5   * This program is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <https://www.gnu.org/licenses/>.
    17   */
    18  
    19  package api_monitoring
    20  
    21  import (
    22  	"encoding/json"
    23  	"github.com/gorilla/mux"
    24  	"net/http"
    25  	"scheduler/errors"
    26  	"scheduler/faas_openfaas"
    27  	"scheduler/log"
    28  	"scheduler/utils"
    29  	"time"
    30  )
    31  
    32  type scaleDelayResponse struct {
    33  	ApproximateDelay float64 `json:"approximate_delay"`
    34  	ErrorMargin      float64 `json:"error_margin"`
    35  	Attempts         int     `json:"attempts"`
    36  }
    37  
    38  // Measure the time of scaling a service.
    39  func ScaleDelay(w http.ResponseWriter, r *http.Request) {
    40  	vars := mux.Vars(r)
    41  	function := vars["function"]
    42  
    43  	// before scaling check if the function is stabilized
    44  	fun, _, err := faas_openfaas.FunctionGet(function)
    45  	if fun.Replicas != fun.AvailableReplicas {
    46  		log.Log.Debugf("Cannot start monitoring, service is not stabilized")
    47  		errors.ReplyWithError(&w, errors.InputNotValid, nil)
    48  		return
    49  	}
    50  
    51  	// scale the function
    52  	_, err = faas_openfaas.FunctionScaleByOne(function)
    53  	if err != nil {
    54  		log.Log.Debugf("Cannot scale function: %s", err.Error())
    55  		errors.ReplyWithError(&w, errors.GenericOpenFaasError, nil)
    56  		return
    57  	}
    58  
    59  	startLoop := time.Now()
    60  	attempts := 0
    61  	var loopTime time.Duration
    62  	// loop until the available replicas is set
    63  	for {
    64  		fun, _, err := faas_openfaas.FunctionGet(function)
    65  		attempts += 1
    66  		if err != nil {
    67  			log.Log.Debugf("Cannot get function: %s", err.Error())
    68  			errors.ReplyWithError(&w, errors.GenericOpenFaasError, nil)
    69  			break
    70  		}
    71  		if fun.Replicas == fun.AvailableReplicas {
    72  			loopTime = time.Since(startLoop)
    73  			break
    74  		}
    75  		time.Sleep(100 * time.Millisecond)
    76  	}
    77  
    78  	// un-scale the function
    79  	_, err = faas_openfaas.FunctionScaleDownByOne(function)
    80  	if err != nil {
    81  		log.Log.Debugf("Cannot scale function: %s", err.Error())
    82  		errors.ReplyWithError(&w, errors.GenericOpenFaasError, nil)
    83  
    84  	}
    85  
    86  	res := &scaleDelayResponse{
    87  		Attempts:         attempts,
    88  		ApproximateDelay: loopTime.Seconds(),
    89  		ErrorMargin:      100,
    90  	}
    91  	resJson, _ := json.Marshal(res)
    92  	utils.HttpSendJSONResponse(&w, http.StatusOK, string(resJson), nil)
    93  }
    94
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