Class: Evinrude::Log

Inherits:
Object
  • Object
show all
Includes:
LoggingHelpers
Defined in:
lib/evinrude/log.rb

Defined Under Namespace

Classes: SnapshottedEntryError, TruncationUnderflowError

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(logger:, snapshot_last_term: 0, snapshot_last_index: 0) ⇒ Log

Returns a new instance of Log.



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# File 'lib/evinrude/log.rb', line 12

def initialize(logger:, snapshot_last_term: 0, snapshot_last_index: 0)
  @logger, @snapshot_last_term, @snapshot_last_index = logger, snapshot_last_term, snapshot_last_index

  @entries = []
end

Instance Attribute Details

#snapshot_last_index ⇒ Object (readonly)

Returns the value of attribute snapshot_last_index.



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# File 'lib/evinrude/log.rb', line 10

def snapshot_last_index
  @snapshot_last_index
end

#snapshot_last_term ⇒ Object (readonly)

Returns the value of attribute snapshot_last_term.



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# File 'lib/evinrude/log.rb', line 10

def snapshot_last_term
  @snapshot_last_term
end

Instance Method Details

#[](n) ⇒ Object 



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# File 'lib/evinrude/log.rb', line 82

def [](n)
  if n == 0
    zeroth_log_entry
  elsif n <= @snapshot_last_index
    raise SnapshottedEntryError
  else
    @entries[n - @snapshot_last_index - 1]
  end
end

#append(entry) ⇒ Object 



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# File 'lib/evinrude/log.rb', line 18

def append(entry)
  logger.debug(logloc) { "Appending new entry #{entry.inspect} as ##{@snapshot_last_index + @entries.length + 1}" }
  @entries << entry

  if @entries.length > 1000
    old_len = @entries.length
    snapshotted_entries = @entries[0..499]
    @entries = @entries[500..]
    @snapshot_last_index += 500
    @snapshot_last_term = snapshotted_entries.last.term
  end
end

#entries_from(n) ⇒ Object 



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# File 'lib/evinrude/log.rb', line 66

def entries_from(n)
  @entries[(n-@snapshot_last_index-1)..] || []
end

#entry_term(n) ⇒ Object 



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# File 'lib/evinrude/log.rb', line 58

def entry_term(n)
  if n == @snapshot_last_index
    @snapshot_last_term
  else
    self[n]&.term
  end
end

#has_entry?(n) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/evinrude/log.rb', line 38

def has_entry?(n)
  n == 0 || n <= @snapshot_last_index + @entries.length
end

#last_entry_term ⇒ Object 



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# File 'lib/evinrude/log.rb', line 50

def last_entry_term
  if @entries.empty?
    @snapshot_last_term
  else
    @entries.last.term
  end
end

#last_index ⇒ Object 



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# File 'lib/evinrude/log.rb', line 46

def last_index
  @entries.length + @snapshot_last_index
end

#new_snapshot(last_term, last_index) ⇒ Object 



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# File 'lib/evinrude/log.rb', line 31

def new_snapshot(last_term, last_index)
  @snapshot_last_term = last_term
  @snapshot_last_index = last_index

  @entries = []
end

#snapshotted_entry?(n) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/evinrude/log.rb', line 42

def snapshotted_entry?(n)
  n > 0 && n <= @snapshot_last_index
end

#truncate_to(n) ⇒ Object

Make the last entry kept in the log the nth.



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# File 'lib/evinrude/log.rb', line 71

def truncate_to(n)
  if n > @snapshot_last_index
    @entries = @entries[0..n-@snapshot_last_index-1]
  elsif n == @snapshot_last_index
    @entries = []
  else
    raise TruncationUnderflowError,
          "Cannot truncate to log entry ##{n}; into the snapshot"
  end
end