Class: SemanticLogger::Appender::MongoDB

Inherits:
Subscriber
  • Object
show all
Defined in:
lib/semantic_logger/appender/mongodb.rb

Overview

The Mongo Appender for the SemanticLogger

Mongo Document Schema:

_id:         ObjectId("4d9cbcbf7abb3abdaf9679cd"),
time:        ISODate("2011-04-06T19:19:27.006Z"),
host:        'Name of the host on which this log entry originated',
application  'Name of application or service logging the data - clarity_base, nginx, tomcat',
pid:         process id
thread:      "name or id of thread",
name:        "com.clarity.MyClass",
level:       'trace|debug|info|warn|error|fatal'
level_index: 0|1|2|3|4|5
message:     "Message supplied to the logging call",
duration:    'human readable duration',
duration_ms: ms,
tags:        ["id1", "id2"]
exception: {
 name:        'MyException',
 message:     'Invalid value',
 stack_trace: []
}
# When a backtrace is captured
file_name:   'my_class.rb'
line_number: 42

Example:

require 'semantic_logger'

appender = SemanticLogger::Appender::MongoDB.new(
uri:             'mongodb://127.0.0.1:27017/test',
collection_size: 1024**3 # 1.gigabyte
)
SemanticLogger.add_appender(appender: appender)

logger = SemanticLogger['Example']

# Log some messages
logger.info 'This message is written to mongo as a document'

Instance Attribute Summary collapse

Attributes inherited from Subscriber

#application, #environment, #formatter, #host, #logger, #metrics

Instance Method Summary collapse

Methods inherited from Subscriber

#batch_by_default?, #close, #console_output?, #console_stream, #flush, #level, #should_log?

Constructor Details

#initialize(uri:, collection_name: "semantic_logger", write_concern: 0, collection_size: 1024**3, collection_max: nil, **args) ⇒ MongoDB

Create a MongoDB Appender instance

Parameters:

uri: [String]
Mongo connection string.
Example:
  mongodb://127.0.0.1:27017/test

collection_name: [String]
Name of the collection to store log data in
Default: semantic_logger

write_concern: [Integer]
Write concern to use
see: http://docs.mongodb.org/manual/reference/write-concern/
Default: 0

collection_size: [Integer]
The size of the MongoDB capped collection to create in bytes
Default: 1 GB
Examples:
  Prod: 25GB (.5GB per day across 4 servers over 10 days)
  Dev: .5GB
  Test: File
  Release: 4GB

collection_max: [Integer]
Maximum number of log entries that the capped collection will hold.
Default: no max limit

level: [:trace | :debug | :info | :warn | :error | :fatal]
Override the log level for this appender.
Default: SemanticLogger.default_level

formatter: [Object|Proc|Symbol]
An instance of a class that implements #call, or a Proc to be used to format
the output from this appender
Default: Use the built-in formatter (See: #call)

filter: [Regexp|Proc]
RegExp: Only include log messages where the class name matches the supplied.
regular expression. All other messages will be ignored.
Proc: Only include log messages where the supplied Proc returns true
      The Proc must return true or false.

host: [String]
Name of this host to appear in log messages.
Default: SemanticLogger.host

application: [String]
Name of this application to appear in log messages.
Default: SemanticLogger.application


104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 104

def initialize(uri:,
               collection_name: "semantic_logger",
               write_concern: 0,
               collection_size: 1024**3,
               collection_max: nil,
               **args,
               &)
  @client          = Mongo::Client.new(uri, logger: logger)
  @collection_name = collection_name
  @options         = {
    capped: true,
    size:   collection_size,
    write:  {w: write_concern}
  }
  @options[:max] = collection_max if collection_max

  reopen

  # Create the collection and necessary indexes
  create_indexes

  super(**args, &)
end

Instance Attribute Details

#client ⇒ Object (readonly)

Returns the value of attribute client.



50
51
52
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 50

def client
  @client
end

#collection ⇒ Object (readonly)

Returns the value of attribute collection.



50
51
52
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 50

def collection
  @collection
end

Instance Method Details

#create_indexes ⇒ Object

Create the required capped collection.

Features of capped collection:

  • No indexes by default (not even on _id)
  • Documents cannot be deleted,
  • Document updates cannot make them any larger
  • Documents are always stored in insertion order
    • A find will always return the documents in their insertion order

Creates an index based on tags to support faster searches.



144
145
146
147
148
149
150
151
152
153
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 144

def create_indexes
  # Create Capped collection
  begin
    @collection.create
  rescue Mongo::Error::OperationFailure
    nil
  end

  @collection.indexes.create_one(tags: 1)
end

#log(log) ⇒ Object

Log the message to MongoDB



165
166
167
168
169
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 165

def log(log)
  # Insert log entry into Mongo
  collection.insert_one(formatter.call(log, self))
  true
end

#purge_all ⇒ Object

Purge all data from the capped collection by dropping the collection and recreating it. Also useful when the size of the capped collection needs to be changed



158
159
160
161
162
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 158

def purge_all
  collection.drop
  reopen
  create_indexes
end

#reopen ⇒ Object

After forking an active process call #reopen to re-open open the handles to resources



130
131
132
 
# File 'lib/semantic_logger/appender/mongodb.rb', line 130

def reopen
  @collection = client[@collection_name, @options]
end