github.com/newrelic/go-agent@v3.26.0+incompatible/internal/cat/appdata.go (about)

     1  // Copyright 2020 New Relic Corporation. All rights reserved.
     2  // SPDX-License-Identifier: Apache-2.0
     3  
     4  package cat
     5  
     6  import (
     7  	"bytes"
     8  	"encoding/json"
     9  	"errors"
    10  
    11  	"github.com/newrelic/go-agent/internal/jsonx"
    12  )
    13  
    14  // AppDataHeader represents a decoded AppData header.
    15  type AppDataHeader struct {
    16  	CrossProcessID        string
    17  	TransactionName       string
    18  	QueueTimeInSeconds    float64
    19  	ResponseTimeInSeconds float64
    20  	ContentLength         int64
    21  	TransactionGUID       string
    22  }
    23  
    24  var (
    25  	errInvalidAppDataJSON                  = errors.New("invalid transaction data JSON")
    26  	errInvalidAppDataCrossProcessID        = errors.New("cross process ID is not a string")
    27  	errInvalidAppDataTransactionName       = errors.New("transaction name is not a string")
    28  	errInvalidAppDataQueueTimeInSeconds    = errors.New("queue time is not a float64")
    29  	errInvalidAppDataResponseTimeInSeconds = errors.New("response time is not a float64")
    30  	errInvalidAppDataContentLength         = errors.New("content length is not a float64")
    31  	errInvalidAppDataTransactionGUID       = errors.New("transaction GUID is not a string")
    32  )
    33  
    34  // MarshalJSON marshalls an AppDataHeader as raw JSON.
    35  func (appData *AppDataHeader) MarshalJSON() ([]byte, error) {
    36  	buf := bytes.NewBufferString("[")
    37  
    38  	jsonx.AppendString(buf, appData.CrossProcessID)
    39  
    40  	buf.WriteString(",")
    41  	jsonx.AppendString(buf, appData.TransactionName)
    42  
    43  	buf.WriteString(",")
    44  	jsonx.AppendFloat(buf, appData.QueueTimeInSeconds)
    45  
    46  	buf.WriteString(",")
    47  	jsonx.AppendFloat(buf, appData.ResponseTimeInSeconds)
    48  
    49  	buf.WriteString(",")
    50  	jsonx.AppendInt(buf, appData.ContentLength)
    51  
    52  	buf.WriteString(",")
    53  	jsonx.AppendString(buf, appData.TransactionGUID)
    54  
    55  	// The mysterious unused field. We don't need to round trip this, so we'll
    56  	// just hardcode it to false.
    57  	buf.WriteString(",false]")
    58  	return buf.Bytes(), nil
    59  }
    60  
    61  // UnmarshalJSON unmarshalls an AppDataHeader from raw JSON.
    62  func (appData *AppDataHeader) UnmarshalJSON(data []byte) error {
    63  	var ok bool
    64  	var v interface{}
    65  
    66  	if err := json.Unmarshal(data, &v); err != nil {
    67  		return err
    68  	}
    69  
    70  	arr, ok := v.([]interface{})
    71  	if !ok {
    72  		return errInvalidAppDataJSON
    73  	}
    74  	if len(arr) < 7 {
    75  		return errUnexpectedArraySize{
    76  			label:    "unexpected number of application data elements",
    77  			expected: 7,
    78  			actual:   len(arr),
    79  		}
    80  	}
    81  
    82  	if appData.CrossProcessID, ok = arr[0].(string); !ok {
    83  		return errInvalidAppDataCrossProcessID
    84  	}
    85  
    86  	if appData.TransactionName, ok = arr[1].(string); !ok {
    87  		return errInvalidAppDataTransactionName
    88  	}
    89  
    90  	if appData.QueueTimeInSeconds, ok = arr[2].(float64); !ok {
    91  		return errInvalidAppDataQueueTimeInSeconds
    92  	}
    93  
    94  	if appData.ResponseTimeInSeconds, ok = arr[3].(float64); !ok {
    95  		return errInvalidAppDataResponseTimeInSeconds
    96  	}
    97  
    98  	cl, ok := arr[4].(float64)
    99  	if !ok {
   100  		return errInvalidAppDataContentLength
   101  	}
   102  	// Content length is specced as int32, but not all agents are consistent on
   103  	// this in practice. Let's handle it as int64 to maximise compatibility.
   104  	appData.ContentLength = int64(cl)
   105  
   106  	if appData.TransactionGUID, ok = arr[5].(string); !ok {
   107  		return errInvalidAppDataTransactionGUID
   108  	}
   109  
   110  	// As above, we don't bother decoding the unused field here. It just has to
   111  	// be present (which was checked earlier with the length check).
   112  
   113  	return nil
   114  }