Class: RQ::QDB

Inherits:
Object
  • Object
show all
Includes:
Logging, Util
Defined in:
lib/rq-3.0.0/qdb.rb

Overview

the QDB class is the low level access point to the actual sqlite database. the primary function if performs is to serialize access to the queue db via the locking protocol

Defined Under Namespace

Classes: AbortedTransactionError, RollbackTransactionError

Constant Summary collapse

FIELDS = 
%w(
  jid priority state 
  submitted started finished elapsed
  submitter runner
  stdin stdout stderr
  pid exit_status
  tag restartable command
)
PRAGMAS =

–}}}

<<-sql
  PRAGMA default_synchronous = FULL;
sql
SCHEMA =

–}}}

<<-sql
  create table jobs
  (
    jid integer primary key,
    #{ FIELDS[1..-1].join ",\n          " }
  );
  create table attributes
  (
    key,
    value,
    primary key (key)
  );
sql
DEFAULT_LOGGER =

–}}}

Logger::new(STDERR)
DEFAULT_SQL_DEBUG = 
false
DEFAULT_TRANSACTION_RETRIES = 
4
DEFAULT_AQUIRE_LOCK_SC = 
SleepCycle::new(2, 16, 2)
DEFAULT_TRANSACTION_RETRIES_SC = 
SleepCycle::new(8, 24, 8)
DEFAULT_ATTEMPT_LOCKD_RECOVERY = 
true
DEFAULT_LOCKD_RECOVER_WAIT =

1 hr

3600
DEFAULT_AQUIRE_LOCK_LOCKFILE_STALE_AGE =

6 hrs

21600
DEFAULT_AQUIRE_LOCK_REFRESH_RATE = 
30

Constants included from Logging

Logging::DIV0, Logging::DIV1, Logging::DIV2, Logging::DIV3, Logging::EOL, Logging::SEC0, Logging::SEC1, Logging::SEC2, Logging::SEC3

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Logging

append_features

Methods included from Logging::LogMethods

#debug, #error, #fatal, #info, #logerr, #logger, #logger=, #warn

Methods included from Util

#alive?, append_features, #btrace, #columnize, #defval, #emsg, #erreq, #errmsg, #escape, #escape!, #exec, export, #fork, #getopt, #hashify, #hms, #host, #hostname, #klass, #maim, #mcp, #realpath, #stamptime, #system, #timestamp, #tmpnam, #uncache, #which_ruby

Constructor Details

#initialize(path, opts = {}) ⇒ QDB

Returns a new instance of QDB.



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# File 'lib/rq-3.0.0/qdb.rb', line 185

def initialize path, opts = {}
#--{{{
  @path = path
  @opts = opts

  @logger = 
    Util::getopt('logger', @opts) || 
    klass.logger || 
    DEFAULT_LOGGER

  @sql_debug = 
    Util::getopt('sql_debug', @opts) || 
    klass.sql_debug || 
    ENV['RQ_SQL_DEBUG'] || 
    DEFAULT_SQL_DEBUG

  @transaction_retries = 
    Util::getopt('transaction_retries', @opts) || 
    klass.transaction_retries ||
    DEFAULT_TRANSACTION_RETRIES

  @aquire_lock_sc =
    Util::getopt('aquire_lock_sc', @opts) ||
    klass.aquire_lock_sc ||
    DEFAULT_AQUIRE_LOCK_SC

  @transaction_retries_sc = 
    Util::getopt('transaction_retries_sc', @opts) ||
    klass.transaction_retries_sc ||
    DEFAULT_TRANSACTION_RETRIES_SC

  @attempt_lockd_recovery = 
    Util::getopt('attempt_lockd_recovery', @opts) ||
    klass.attempt_lockd_recovery ||
    DEFAULT_ATTEMPT_LOCKD_RECOVERY

  @lockd_recover_wait = 
    Util::getopt('lockd_recover_wait', @opts) ||
    klass.lockd_recover_wait ||
    DEFAULT_LOCKD_RECOVER_WAIT

  @aquire_lock_lockfile_stale_age = 
    Util::getopt('aquire_lock_lockfile_stale_age', @opts) ||
    klass.aquire_lock_lockfile_stale_age ||
    DEFAULT_AQUIRE_LOCK_LOCKFILE_STALE_AGE

  @aquire_lock_refresh_rate = 
    Util::getopt('aquire_lock_refresh_rate', @opts) ||
    klass.aquire_lock_refresh_rate ||
    DEFAULT_AQUIRE_LOCK_REFRESH_RATE


  @schema = "#{ @path }.schema"
  @dirname = File::dirname(path).gsub(%r|/+\s*$|,'')
  @basename = File::basename(path)
  @waiting_w = File::join(@dirname, "#{ Util::hostname }.#{ $$ }.waiting.w") 
  @waiting_r = File::join(@dirname, "#{ Util::hostname }.#{ $$ }.waiting.r") 
  @lock_w = File::join(@dirname, "#{ Util::hostname }.#{ $$ }.lock.w") 
  @lock_r = File::join(@dirname, "#{ Util::hostname }.#{ $$ }.lock.r") 
  @lockfile = File::join(@dirname, 'lock') 
  @lockf = Lockfile::new("#{ @path }.lock") 
  @fields = FIELDS
  @in_transaction = false
  @in_ro_transaction = false
  @db = nil

  @lockd_recover = "#{ @dirname }.lockd_recover"
  @lockd_recover_lockf = Lockfile::new "#{ @lockd_recover }.lock"
  @lockd_recovered = false
#--}}}
end

Class Attribute Details

.aquire_lock_lockfile_stale_age ⇒ Object

Returns the value of attribute aquire_lock_lockfile_stale_age.



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# File 'lib/rq-3.0.0/qdb.rb', line 81

def aquire_lock_lockfile_stale_age
  @aquire_lock_lockfile_stale_age
end

.aquire_lock_refresh_rate ⇒ Object

Returns the value of attribute aquire_lock_refresh_rate.



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# File 'lib/rq-3.0.0/qdb.rb', line 82

def aquire_lock_refresh_rate
  @aquire_lock_refresh_rate
end

.aquire_lock_sc ⇒ Object

Returns the value of attribute aquire_lock_sc.



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# File 'lib/rq-3.0.0/qdb.rb', line 77

def aquire_lock_sc
  @aquire_lock_sc
end

.attempt_lockd_recovery ⇒ Object

Returns the value of attribute attempt_lockd_recovery.



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# File 'lib/rq-3.0.0/qdb.rb', line 79

def attempt_lockd_recovery
  @attempt_lockd_recovery
end

.lockd_recover_wait ⇒ Object

Returns the value of attribute lockd_recover_wait.



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# File 'lib/rq-3.0.0/qdb.rb', line 80

def lockd_recover_wait
  @lockd_recover_wait
end

.sql_debug ⇒ Object

–{{{



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# File 'lib/rq-3.0.0/qdb.rb', line 75

def sql_debug
  @sql_debug
end

.transaction_retries ⇒ Object

Returns the value of attribute transaction_retries.



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# File 'lib/rq-3.0.0/qdb.rb', line 76

def transaction_retries
  @transaction_retries
end

.transaction_retries_sc ⇒ Object

Returns the value of attribute transaction_retries_sc.



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# File 'lib/rq-3.0.0/qdb.rb', line 78

def transaction_retries_sc
  @transaction_retries_sc
end

Instance Attribute Details

#aquire_lock_lockfile_stale_age ⇒ Object

Returns the value of attribute aquire_lock_lockfile_stale_age.



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# File 'lib/rq-3.0.0/qdb.rb', line 181

def aquire_lock_lockfile_stale_age
  @aquire_lock_lockfile_stale_age
end

#aquire_lock_refresh_rate ⇒ Object

Returns the value of attribute aquire_lock_refresh_rate.



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# File 'lib/rq-3.0.0/qdb.rb', line 182

def aquire_lock_refresh_rate
  @aquire_lock_refresh_rate
end

#aquire_lock_sc ⇒ Object

Returns the value of attribute aquire_lock_sc.



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# File 'lib/rq-3.0.0/qdb.rb', line 177

def aquire_lock_sc
  @aquire_lock_sc
end

#attempt_lockd_recovery ⇒ Object

Returns the value of attribute attempt_lockd_recovery.



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# File 'lib/rq-3.0.0/qdb.rb', line 179

def attempt_lockd_recovery
  @attempt_lockd_recovery
end

#dirname ⇒ Object (readonly)

Returns the value of attribute dirname.



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# File 'lib/rq-3.0.0/qdb.rb', line 170

def dirname
  @dirname
end

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/rq-3.0.0/qdb.rb', line 172

def fields
  @fields
end

#lockd_recover_wait ⇒ Object

Returns the value of attribute lockd_recover_wait.



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# File 'lib/rq-3.0.0/qdb.rb', line 180

def lockd_recover_wait
  @lockd_recover_wait
end

#lockfile ⇒ Object (readonly)

Returns the value of attribute lockfile.



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# File 'lib/rq-3.0.0/qdb.rb', line 174

def lockfile
  @lockfile
end

#mutex ⇒ Object (readonly)

Returns the value of attribute mutex.



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# File 'lib/rq-3.0.0/qdb.rb', line 173

def mutex
  @mutex
end

#opts ⇒ Object (readonly)

Returns the value of attribute opts.



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# File 'lib/rq-3.0.0/qdb.rb', line 169

def opts
  @opts
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/rq-3.0.0/qdb.rb', line 168

def path
  @path
end

#schema ⇒ Object (readonly)

Returns the value of attribute schema.



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# File 'lib/rq-3.0.0/qdb.rb', line 171

def schema
  @schema
end

#sql_debug ⇒ Object

Returns the value of attribute sql_debug.



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# File 'lib/rq-3.0.0/qdb.rb', line 175

def sql_debug
  @sql_debug
end

#transaction_retries ⇒ Object

Returns the value of attribute transaction_retries.



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# File 'lib/rq-3.0.0/qdb.rb', line 176

def transaction_retries
  @transaction_retries
end

#transaction_retries_sc ⇒ Object

Returns the value of attribute transaction_retries_sc.



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# File 'lib/rq-3.0.0/qdb.rb', line 178

def transaction_retries_sc
  @transaction_retries_sc
end

Class Method Details

.create(path, opts = {}) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 143

def create path, opts = {}
#--{{{
  qdb = new path, opts
  FileUtils::touch qdb.lockfile
  create_schema qdb.schema
  qdb.transaction do 
    qdb.execute PRAGMAS
    qdb.execute SCHEMA
  end
  qdb
#--}}}
end

.create_schema(path) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 155

def create_schema path
#--{{{
  tmp = "#{ path }.tmp"
  open(tmp,'w') do |f| 
    f.puts PRAGMAS 
    f.puts SCHEMA
  end
  FileUtils::mv tmp, path
#--}}}
end

.fields ⇒ Object 



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# File 'lib/rq-3.0.0/qdb.rb', line 84

def fields
#--{{{
  FIELDS
#--}}}
end

.h2t(h) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 118

def h2t h
#--{{{
  t = tuple
  FIELDS.each{|f| t[f] = h[f]}
  t
#--}}}
end

.integrity_check(dbpath) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 89

def integrity_check dbpath
#--{{{
  ret = false 
  tuple = nil
  begin
    db = 
      begin
        SQLite::Database::new dbpath, 0
      rescue
        SQLite::Database::new dbpath
      end
    opened = true
    db.use_array = true rescue nil
    tuple = db.execute 'PRAGMA integrity_check;'
    ret = (tuple and tuple.first and (tuple.first["integrity_check"] =~ /^\s*ok\s*$/io))
  ensure
    db.close if opened
    db = nil
  end
  ret
#--}}}
end

.q(tuple) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 132

def q tuple
#--{{{
  [ tuple ].flatten.map do |f| 
    if f and not f.to_s.empty?
      "'" << Util.escape(f,"'","'") << "'"
    else
      'NULL'
    end
  end
#--}}}
end

.t2h(tuple) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 111

def t2h tuple
#--{{{
  h = {}
  FIELDS.each_with_index{|f,i| h[f] = tuple[i]}
  h
#--}}}
end

.tuple ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 125

def tuple
#--{{{
  t = Array::new FIELDS.size
  t.fields = FIELDS
  t
#--}}}
end

Instance Method Details

#abort_transaction(*a) ⇒ Object

–}}}

Raises:



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# File 'lib/rq-3.0.0/qdb.rb', line 410

def abort_transaction(*a)
#--{{{
  raise AbortedTransactionError, *a
#--}}}
end

#aquire_lock(opts = {}) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 437

def aquire_lock opts = {} 
#--{{{
  ro = Util::getopt 'read_only', opts
  ret = nil

  @aquire_lock_sc.reset
    
  waiting, ltype, lfile =
    if ro
      [@waiting_r, File::LOCK_SH | File::LOCK_NB, @lock_r]
    else
      [@waiting_w, File::LOCK_EX | File::LOCK_NB, @lock_w]
    end
    
  ltype_s = (ltype == File::LOCK_EX ? 'write' : 'read')
  ltype ||= File::LOCK_NB

  aquired = false

  until aquired
    begin
      debug{ "aquiring lock" }
      #@lockf.lock unless ro

      open(@lockfile, 'a+') do |lf|

        locked = false
        refresher = nil
        sc = nil

        begin
          FileUtils::touch waiting
          # poll
          42.times do
            locked = lf.posixlock(ltype | File::LOCK_NB)
            break if locked
            sleep rand
          end

          if locked
            aquired = true
            refresher = Refresher::new @lockfile, @aquire_lock_refresh_rate
            debug{ "refresher pid <#{ refresher.pid }> refresh_rate <#{ @aquire_lock_refresh_rate }>" }
            FileUtils::rm_f waiting rescue nil
            FileUtils::touch lfile rescue nil
            debug{ "aquired lock" }
            ret = yield
            debug{ "released lock" }
          else
            aquired = false 
            stat = File::stat @lockfile
            mtime = stat.mtime
            stale = mtime < (Time::now - @aquire_lock_lockfile_stale_age)
            if stale
              Util::uncache @lockfile rescue nil
              stat = File::stat @lockfile
              mtime = stat.mtime
              stale = mtime < (Time::now - @aquire_lock_lockfile_stale_age)
              if stale
                warn{ "detected stale lockfile of mtime <#{ mtime }>" }
                lockd_recover if @attempt_lockd_recovery
              end
            end
            sc = @aquire_lock_sc.next
            debug{ "failed to aquire lock - sleep(#{ sc })" }
            sleep sc 
          end

        ensure
          if locked
            unlocked = false
            begin
              42.times do
                unlocked = lf.posixlock(File::LOCK_UN | File::LOCK_NB)
                break if unlocked
                sleep rand
              end
            ensure
              lf.posixlock File::LOCK_UN unless unlocked
            end
          end
          refresher.kill if refresher
          FileUtils::rm_f waiting rescue nil
          FileUtils::rm_f lfile rescue nil 
        end
      end
    ensure
      #@lockf.unlock rescue nil unless read_only
    end
  end
  ret
#--}}}
end

#connect ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 530

def connect
#--{{{
  ret = nil
  opened = nil
  begin
    raise 'db has no schema' unless test ?e, @schema
    debug{"connecting to db <#{ @path }>..."}
    $db = @db = 
      begin
        SQLite::Database::new(@path, 0)
      rescue
        SQLite::Database::new(@path)
      end
    debug{"connected."}
    opened = true
    @db.use_array = true rescue nil
    ret = yield @db
  ensure
    @db.close if opened
    $db = @db = nil
    debug{"disconnected from db <#{ @path }>"}
  end
  ret
#--}}}
end

#execute(sql, &block) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 555

def execute sql, &block
#--{{{
  raise 'not in transaction' unless @in_transaction
  if @sql_debug
    logger << "SQL:\n#{ sql }\n"
  end
  #ret = retry_if_locked{ @db.execute sql, &block }
  ret = @db.execute sql, &block
  if @sql_debug and ret and Array === ret and ret.first
    logger << "RESULT:\n#{ ret.first.inspect }\n...\n"
  end
  ret
#--}}}
end

#integrity_check(path = @path) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 702

def integrity_check path = @path
#--{{{
  debug{ "running integrity_check on <#{ path }>" }
  klass.integrity_check(path)  
#--}}}
end

#lock(opts = {}) ⇒ Object Also known as: write_lock

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 708

def lock opts = {} 
#--{{{
  ret = nil
  lockd_recover_wrap do
    aquire_lock(opts) do
      ret = yield 
    end
  end
  ret
#--}}}
end

#lockd_recover ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 611

def lockd_recover
#--{{{
  return nil unless @attempt_lockd_recovery
  warn{ "attempting lockd recovery" }
  time = Time::now
  ret = nil

  @lockd_recover_lockf.lock do
    Util::uncache @dirname rescue nil
    Util::uncache @path rescue nil
    Util::uncache @lockfile rescue nil
    Util::uncache @lockd_recover rescue nil
    mtime = File::stat(@lockd_recover).mtime rescue time

    if mtime > time 
      warn{ "skipping lockd recovery (another node has already recovered)" }
      ret = true
    else
      moved = false
      begin
        FileUtils::touch @lockd_recover 
        @lockd_recovered = false 

        begin
          report = <<-msg
            hostname : #{ Util::hostname }
            pid      : #{ Process.pid }
            time     : #{ Time::now }
            q        : 
              path : #{ @dirname }
              stat : #{ File::stat(@dirname).inspect }
            db       : 
              path : #{ @path }
              stat : #{ File::stat(@path).inspect }
            lockfile : 
              path : #{ @lockfile }
              stat : #{ File::stat(@lockfile).inspect }
          msg
          info{ "LOCKD RECOVERY REPORT" }
          logger << report
          cmd = "mail -s LOCKD_RECOVERY [email protected] <<eof\n#{ report }\neof"
          Util::system cmd
        rescue
          nil
        end

        warn{ "sleeping #{ @lockd_recover_wait }s before continuing..." }
        sleep @lockd_recover_wait 

        tmp = "#{ @dirname }.tmp"
        FileUtils::rm_rf tmp
        FileUtils::mv @dirname, tmp
        moved = true

        rfiles = [@path, @lockfile].map{|f| File::join(tmp,File::basename(f))}
        rfiles.each do |f|
          ftmp = "#{ f }.tmp"
          FileUtils::rm_rf ftmp
          FileUtils::cp f, ftmp 
          FileUtils::rm f 
          FileUtils::mv ftmp, f 
        end

        dbtmp = File::join(tmp,File::basename(@path))

        if integrity_check(dbtmp)
          FileUtils::mv tmp, @dirname
          FileUtils::cp @lockd_recover_lockf.path, @lockd_recover 
          @lockd_recovered = true 
          Util::uncache @dirname rescue nil
          Util::uncache @path rescue nil
          Util::uncache @lockfile rescue nil
          Util::uncache @lockd_recover rescue nil
          warn{ "lockd recovery complete" }
        else
          FileUtils::mv tmp, @dirname
          @lockd_recovered = false 
          error{ "lockd recovery failed" }
        end

        ret = @lockd_recovered 
      ensure
        if moved and not @lockd_recovered and tmp and test(?d, tmp)
          FileUtils::mv tmp, @dirname
        end
      end
    end
  end
  ret
#--}}}
end

#lockd_recover_wrap(opts = {}) ⇒ Object 



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# File 'lib/rq-3.0.0/qdb.rb', line 327

def lockd_recover_wrap opts = {}
#--{{{
  ret = nil
  try_again = false
  begin
    begin
      @lockd_recovered = false
      old_mtime = 
        begin
          Util::uncache @lockd_recover rescue nil
          File::stat(@lockd_recover).mtime
        rescue
          Time::now 
        end
      ret = yield
    ensure
      new_mtime =
        begin
          Util::uncache @lockd_recover rescue nil
          File::stat(@lockd_recover).mtime
        rescue
          old_mtime
        end

      if new_mtime and old_mtime and new_mtime > old_mtime and not @lockd_recovered
        try_again = true
      end
    end
  rescue
    if try_again
      warn{ "a remote lockd recovery has invalidated this transaction!" }
      warn{ "retrying..."}
      sleep 120
      retry
    else
      raise
    end
  end
  ret
#--}}}
end

#read_lock(opts = {}, &block) ⇒ Object Also known as: rlock 



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# File 'lib/rq-3.0.0/qdb.rb', line 721

def read_lock(opts = {}, &block)
#--{{{
  opts['read_only'] = true
  lock opts, &block
#--}}}
end

#recover! ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 597

def recover!
#--{{{
  raise 'nested transaction' if @in_transaction
  begin 
    @in_transaction = true
    connect{ execute 'vacuum' }
    require 'timeout'
    Timeout::timeout(60){ system "sqlite #{ @path } .tables >/dev/null 2>&1" }
  ensure
    @in_transaction = false
  end
  integrity_check
#--}}}
end

#retry_if_locked ⇒ Object

TODO - add sleep cycle if this ends up getting used



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# File 'lib/rq-3.0.0/qdb.rb', line 572

def retry_if_locked
#--{{{
  ret = nil
  begin
    ret = yield 
  rescue SQLite::BusyException
    warn{ "database locked - waiting(1.0) and retrying" }
    sleep 1.0 
    retry
  end
  ret
#--}}}
end

#ro_transaction(opts = {}, &block) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 256

def ro_transaction(opts = {}, &block)
#--{{{
  opts['read_only'] = true
  transaction(opts, &block)
#--}}}
end

#rollback_transaction(*a) ⇒ Object

–}}}

Raises:



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# File 'lib/rq-3.0.0/qdb.rb', line 415

def rollback_transaction(*a)
#--{{{
  raise RollbackTransactionError, *a
#--}}}
end

#sillyclean(opts = {}) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 420

def sillyclean opts = {} 
#--{{{
  ro = Util::getopt 'read_only', opts
  ret = nil
  if ro
    ret = yield
  else
    glob = File::join @dirname,'.nfs*'
    orgsilly = Dir[glob]
    ret = yield
    newsilly = Dir[glob]
    silly = newsilly - orgsilly 
    silly.each{|path| FileUtils::rm_rf path}
  end
  ret
#--}}}
end

#transaction(opts = {}) ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 262

def transaction opts = {} 
#--{{{
  raise 'nested transaction' if @in_transaction
  ro = Util::getopt 'read_only', opts 
  ret = nil
  begin 
    @in_transaction = true
    lockd_recover_wrap(opts) do
      transaction_wrap(opts) do
        aquire_lock(opts) do
          #sillyclean(opts) do
            connect do
              execute 'begin' unless ro
              ret = yield 
              execute 'commit' unless ro
            end
          #end
        end
      end
    end
  ensure
    @in_transaction = false
  end
  ret
#--}}}
end

#transaction_wrap(opts = {}) ⇒ Object

simply retry.



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# File 'lib/rq-3.0.0/qdb.rb', line 373

def transaction_wrap opts = {} 
#--{{{
  ro = Util::getopt 'read_only', opts
  ret = nil
  if ro
    ret = yield 
  else
    errors = []
    @transaction_retries_sc.reset
    begin
      ret = yield 
    rescue => e
    #rescue SQLite::DatabaseException, SQLite::SQLException, SystemCallError => e
      case e
        when AbortedTransactionError 
          raise
        when RollbackTransactionError 
          raise
        else
          if @transaction_retries == 0
            raise
          elsif errors.size >= @transaction_retries
            error{ "MAXIMUM TRANSACTION RETRIES SURPASSED" }
            raise
          else
            warn{ e } if(errors.empty? or not Util::erreq(errors[-1], e))
            errors << e
            warn{ "retry <#{ errors.size }>..." }
          end
          sleep @transaction_retries_sc.next
          retry
        end
    end
  end
  ret
#--}}}
end

#vacuum ⇒ Object

–}}}



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# File 'lib/rq-3.0.0/qdb.rb', line 585

def vacuum
#--{{{
  raise 'nested transaction' if @in_transaction
  begin 
    @in_transaction = true
    connect{ execute 'vacuum' }
  ensure
    @in_transaction = false
  end
  self
#--}}}
end