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workitems.cc
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workitems.cc
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// -------------------------------------------------------------------
//
// eleveldb: Erlang Wrapper for LevelDB (http://code.google.com/p/leveldb/)
//
// Copyright (c) 2011-2015 Basho Technologies, Inc. All Rights Reserved.
//
// This file is provided to you under the Apache License,
// Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
//
// -------------------------------------------------------------------
#include <syslog.h>
#ifndef INCL_WORKITEMS_H
#include "workitems.h"
#endif
#include "leveldb/atomics.h"
#include "leveldb/cache.h"
#include "leveldb/filter_policy.h"
#include "leveldb/perf_count.h"
// error_tuple duplicated in workitems.cc and eleveldb.cc ... how to fix?
static ERL_NIF_TERM error_tuple(ErlNifEnv* env, ERL_NIF_TERM error, leveldb::Status& status)
{
ERL_NIF_TERM reason = enif_make_string(env, status.ToString().c_str(),
ERL_NIF_LATIN1);
return enif_make_tuple2(env, eleveldb::ATOM_ERROR,
enif_make_tuple2(env, error, reason));
}
static ERL_NIF_TERM slice_to_binary(ErlNifEnv* env, leveldb::Slice s)
{
ERL_NIF_TERM result;
unsigned char* value = enif_make_new_binary(env, s.size(), &result);
memcpy(value, s.data(), s.size());
return result;
}
namespace eleveldb {
/**
* WorkTask functions
*/
WorkTask::WorkTask(ErlNifEnv *caller_env, ERL_NIF_TERM& caller_ref)
: terms_set(false)
{
if (NULL!=caller_env)
{
local_env_ = enif_alloc_env();
caller_ref_term = enif_make_copy(local_env_, caller_ref);
caller_pid_term = enif_make_pid(local_env_, enif_self(caller_env, &local_pid));
terms_set=true;
} // if
else
{
local_env_=NULL;
terms_set=false;
} // else
return;
} // WorkTask::WorkTask
WorkTask::WorkTask(ErlNifEnv *caller_env, ERL_NIF_TERM& caller_ref, DbObject * DbPtr)
: m_DbPtr(DbPtr), terms_set(false)
{
if (NULL!=caller_env)
{
local_env_ = enif_alloc_env();
caller_ref_term = enif_make_copy(local_env_, caller_ref);
caller_pid_term = enif_make_pid(local_env_, enif_self(caller_env, &local_pid));
terms_set=true;
} // if
else
{
local_env_=NULL;
terms_set=false;
} // else
return;
} // WorkTask::WorkTask
WorkTask::~WorkTask()
{
ErlNifEnv * env_ptr;
// this is likely overkill in the present code, but seemed
// important at one time and leaving for safety
env_ptr=local_env_;
if (leveldb::compare_and_swap(&local_env_, env_ptr, (ErlNifEnv *)NULL)
&& NULL!=env_ptr)
{
enif_free_env(env_ptr);
} // if
return;
} // WorkTask::~WorkTask
void
WorkTask::operator()()
{
// call the DoWork() method defined by the subclass
basho::async_nif::work_result result = DoWork();
if (result.is_set())
{
ErlNifPid pid;
if(0 != enif_get_local_pid(this->local_env(), this->pid(), &pid))
{
/* Assemble a notification of the following form:
{ PID CallerHandle, ERL_NIF_TERM result } */
ERL_NIF_TERM result_tuple = enif_make_tuple2(this->local_env(),
this->caller_ref(),
result.result());
enif_send(0, &pid, this->local_env(), result_tuple);
}
}
}
/**
* OpenTask functions
*/
OpenTask::OpenTask(
ErlNifEnv* caller_env,
ERL_NIF_TERM& _caller_ref,
const std::string& db_name_,
leveldb::Options *open_options_)
: WorkTask(caller_env, _caller_ref),
db_name(db_name_), open_options(open_options_)
{
} // OpenTask::OpenTask
work_result
OpenTask::DoWork()
{
void * db_ptr_ptr;
leveldb::DB *db(0);
leveldb::Status status = leveldb::DB::Open(*open_options, db_name, &db);
if(!status.ok())
return error_tuple(local_env(), ATOM_ERROR_DB_OPEN, status);
db_ptr_ptr=DbObject::CreateDbObject(db, open_options);
// create a resource reference to send erlang
ERL_NIF_TERM result = enif_make_resource(local_env(), db_ptr_ptr);
// clear the automatic reference from enif_alloc_resource in CreateDbObject
enif_release_resource(db_ptr_ptr);
return work_result(local_env(), ATOM_OK, result);
} // OpenTask::DoWork()
/**
* MoveTask functions
*/
work_result
MoveTask::DoWork()
{
leveldb::Iterator* itr;
itr=m_ItrWrap->get();
++m_ItrWrap->m_MoveCount;
//
// race condition of prefetch clearing db iterator while
// async_iterator_move looking at it.
//
// iterator_refresh operation
if (m_ItrWrap->m_Options.iterator_refresh && m_ItrWrap->m_StillUse)
{
struct timeval tv;
gettimeofday(&tv, NULL);
if (m_ItrWrap->m_IteratorStale < tv.tv_sec || NULL==itr)
{
m_ItrWrap->RebuildIterator();
itr=m_ItrWrap->get();
// recover position
if (NULL!=itr && 0!=m_ItrWrap->m_RecentKey.size())
{
leveldb::Slice key_slice(m_ItrWrap->m_RecentKey);
itr->Seek(key_slice);
m_ItrWrap->m_StillUse=itr->Valid();
if (!m_ItrWrap->m_StillUse)
{
itr=NULL;
m_ItrWrap->PurgeIterator();
} // if
} // if
} // if
} // if
// hung iterator debug
{
struct timeval tv;
gettimeofday(&tv, NULL);
// 14400 is 4 hours in seconds ... 60*60*4
if ((m_ItrWrap->m_LastLogReport + 14400) < tv.tv_sec && NULL!=m_ItrWrap->get())
{
m_ItrWrap->LogIterator();
m_ItrWrap->m_LastLogReport=tv.tv_sec;
} // if
}
// back to normal operation
if(NULL == itr)
return work_result(local_env(), ATOM_ERROR, ATOM_ITERATOR_CLOSED);
switch(action)
{
case FIRST: itr->SeekToFirst(); break;
case LAST: itr->SeekToLast(); break;
case PREFETCH:
case PREFETCH_STOP:
case NEXT: if(itr->Valid()) itr->Next(); break;
case PREV: if(itr->Valid()) itr->Prev(); break;
case SEEK:
{
leveldb::Slice key_slice(seek_target);
itr->Seek(key_slice);
break;
} // case
default:
// JFW: note: *not* { ERROR, badarg() } here-- we want the exception:
// JDB: note: We can't send an exception as a message. It crashes Erlang.
// Changing to be {error, badarg}.
return work_result(local_env(), ATOM_ERROR, ATOM_BADARG);
break;
} // switch
// set state for Erlang side to read
m_ItrWrap->SetValid(itr->Valid());
// Post processing before telling the world the results
// (while only one thread might be looking at objects)
if (m_ItrWrap->m_Options.iterator_refresh)
{
if (itr->Valid())
{
m_ItrWrap->m_RecentKey.assign(itr->key().data(), itr->key().size());
} // if
else if (PREFETCH_STOP!=action)
{
// release iterator now, not later
m_ItrWrap->m_StillUse=false;
m_ItrWrap->PurgeIterator();
itr=NULL;
} // else
} // if
// debug syslog(LOG_ERR, " MoveItem::DoWork() %d, %d, %d",
// action, m_ItrWrap->m_StillUse, m_ItrWrap->m_HandoffAtomic);
// who got back first, us or the erlang loop
if (leveldb::compare_and_swap(&m_ItrWrap->m_HandoffAtomic, 0, 1))
{
// this is prefetch of next iteration. It returned faster than actual
// request to retrieve it. Stop and wait for erlang to catch up.
// (even if this result is an Invalid() )
} // if
else
{
// setup next race for the response
m_ItrWrap->m_HandoffAtomic=0;
if(NULL!=itr && itr->Valid())
{
if (PREFETCH==action && m_ItrWrap->m_PrefetchStarted)
m_ResubmitWork=true;
// erlang is waiting, send message
if(m_ItrWrap->m_KeysOnly)
return work_result(local_env(), ATOM_OK, slice_to_binary(local_env(), itr->key()));
return work_result(local_env(), ATOM_OK,
slice_to_binary(local_env(), itr->key()),
slice_to_binary(local_env(), itr->value()));
} // if
else
{
// using compare_and_swap as a hardware locking "set to false"
// (a little heavy handed, but not executed often)
leveldb::compare_and_swap(&m_ItrWrap->m_PrefetchStarted, (int)true, (int)false);
return work_result(local_env(), ATOM_ERROR, ATOM_INVALID_ITERATOR);
} // else
} // else
return(work_result());
}
ErlNifEnv *
MoveTask::local_env()
{
if (NULL==local_env_)
local_env_ = enif_alloc_env();
if (!terms_set)
{
caller_ref_term = enif_make_copy(local_env_, m_ItrWrap->itr_ref);
caller_pid_term = enif_make_pid(local_env_, &local_pid);
terms_set=true;
} // if
return(local_env_);
} // MoveTask::local_env
void
MoveTask::recycle()
{
// test for race condition of simultaneous delete & recycle
if (1<RefInc())
{
if (NULL!=local_env_)
enif_clear_env(local_env_);
terms_set=false;
m_ResubmitWork=false;
// only do this in non-race condition
RefDec();
} // if
else
{
// touch NOTHING
} // else
} // MoveTask::recycle
/**
* DestroyTask functions
*/
DestroyTask::DestroyTask(
ErlNifEnv* caller_env,
ERL_NIF_TERM& _caller_ref,
const std::string& db_name_,
leveldb::Options *open_options_)
: WorkTask(caller_env, _caller_ref),
db_name(db_name_), open_options(open_options_)
{
} // DestroyTask::DestroyTask
work_result
DestroyTask::DoWork()
{
leveldb::Status status = leveldb::DestroyDB(db_name, *open_options);
if(!status.ok())
return error_tuple(local_env(), ATOM_ERROR_DB_DESTROY, status);
return work_result(ATOM_OK);
} // DestroyTask::DoWork()
} // namespace eleveldb