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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, DbObjectPtr_t & 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()
/**
* WriteTask functions
*/
WriteTask::WriteTask(ErlNifEnv* _owner_env, ERL_NIF_TERM _caller_ref,
DbObjectPtr_t & _db_handle,
leveldb::WriteBatch* _batch,
leveldb::WriteOptions* _options)
: WorkTask(_owner_env, _caller_ref, _db_handle),
batch(_batch),
options(_options)
{}
WriteTask::~WriteTask()
{
delete batch;
delete options;
}
work_result
WriteTask::DoWork()
{
leveldb::Status status = m_DbPtr->m_Db->Write(*options, batch);
return (status.ok() ? work_result(ATOM_OK) : work_result(local_env(), ATOM_ERROR_DB_WRITE, status));
}
/**
* GetTask functions
*/
GetTask::GetTask(ErlNifEnv *_caller_env,
ERL_NIF_TERM _caller_ref,
DbObjectPtr_t & _db_handle,
ERL_NIF_TERM _key_term,
leveldb::ReadOptions &_options)
: WorkTask(_caller_env, _caller_ref, _db_handle),
options(_options)
{
ErlNifBinary key;
enif_inspect_binary(_caller_env, _key_term, &key);
m_Key.assign((const char *)key.data, key.size);
}
GetTask::~GetTask() {}
work_result
GetTask::DoWork()
{
ERL_NIF_TERM value_bin;
BinaryValue value(local_env(), value_bin);
leveldb::Slice key_slice(m_Key);
leveldb::Status status = m_DbPtr->m_Db->Get(options, key_slice, &value);
if(!status.ok()){
if ( status.IsNotFound() )
return work_result(ATOM_NOT_FOUND);
else
return work_result(local_env(), ATOM_ERROR, status);
}
return work_result(local_env(), ATOM_OK, value_bin);
}
/**
* IterTask functions
*/
IterTask::IterTask(ErlNifEnv *_caller_env,
ERL_NIF_TERM _caller_ref,
DbObjectPtr_t & _db_handle,
const bool _keys_only,
leveldb::ReadOptions &_options)
: WorkTask(_caller_env, _caller_ref, _db_handle),
keys_only(_keys_only), options(_options)
{}
IterTask::~IterTask() {}
work_result
IterTask::DoWork()
{
ItrObject * itr_ptr=0;
void * itr_ptr_ptr=0;
// NOTE: transferring ownership of options to ItrObject
itr_ptr_ptr=ItrObject::CreateItrObject(m_DbPtr, keys_only, options);
// Copy caller_ref to reuse in future iterator_move calls
itr_ptr=((ItrObjErlang*)itr_ptr_ptr)->m_ItrPtr;
itr_ptr->itr_ref_env = enif_alloc_env();
itr_ptr->itr_ref = enif_make_copy(itr_ptr->itr_ref_env, caller_ref());
ERL_NIF_TERM result = enif_make_resource(local_env(), itr_ptr_ptr);
// release reference created during CreateItrObject()
enif_release_resource(itr_ptr_ptr);
return work_result(local_env(), ATOM_OK, result);
} // operator()
/**
* MoveTask functions
*/
// Constructor with no seek target:
MoveTask::MoveTask(ErlNifEnv *_caller_env, ERL_NIF_TERM _caller_ref,
ItrObjectPtr_t & Iter, action_t& _action)
: WorkTask(NULL, _caller_ref, Iter->m_DbPtr),
m_Itr(Iter), action(_action)
{
// special case construction
local_env_=NULL;
enif_self(_caller_env, &local_pid);
}
// Constructor with seek target:
MoveTask::MoveTask(ErlNifEnv *_caller_env, ERL_NIF_TERM _caller_ref,
ItrObjectPtr_t & Iter, action_t& _action,
std::string& _seek_target)
: WorkTask(NULL, _caller_ref, Iter->m_DbPtr),
m_Itr(Iter), action(_action),
seek_target(_seek_target)
{
// special case construction
local_env_=NULL;
enif_self(_caller_env, &local_pid);
}
MoveTask::~MoveTask() {};
work_result
MoveTask::DoWork()
{
leveldb::Iterator* itr;
itr=m_Itr->m_Wrap.get();
//
// race condition of prefetch clearing db iterator while
// async_iterator_move looking at it.
//
// iterator_refresh operation
if (m_Itr->m_Wrap.m_Options.iterator_refresh && m_Itr->m_Wrap.m_StillUse)
{
struct timeval tv;
gettimeofday(&tv, NULL);
if (m_Itr->m_Wrap.m_IteratorStale < tv.tv_sec || NULL==itr)
{
m_Itr->m_Wrap.RebuildIterator();
itr=m_Itr->m_Wrap.get();
// recover position
if (NULL!=itr && 0!=m_Itr->m_Wrap.m_RecentKey.size())
{
leveldb::Slice key_slice(m_Itr->m_Wrap.m_RecentKey);
itr->Seek(key_slice);
m_Itr->m_Wrap.m_StillUse=itr->Valid();
if (!m_Itr->m_Wrap.m_StillUse)
{
itr=NULL;
m_Itr->m_Wrap.PurgeIterator();
} // if
} // if
} // if
} // 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_Itr->m_Wrap.SetValid(itr->Valid());
// Post processing before telling the world the results
// (while only one thread might be looking at objects)
if (m_Itr->m_Wrap.m_Options.iterator_refresh)
{
if (itr->Valid())
{
m_Itr->m_Wrap.m_RecentKey.assign(itr->key().data(), itr->key().size());
} // if
else if (PREFETCH_STOP!=action)
{
// release iterator now, not later
m_Itr->m_Wrap.m_StillUse=false;
m_Itr->m_Wrap.PurgeIterator();
itr=NULL;
} // else
} // if
// debug syslog(LOG_ERR, " MoveItem::DoWork() %d, %d, %d",
// action, m_Itr->m_Wrap.m_StillUse, m_Itr->m_Wrap.m_HandoffAtomic);
// who got back first, us or the erlang loop
if (leveldb::compare_and_swap(&m_Itr->m_Wrap.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_Itr->m_Wrap.m_HandoffAtomic=0;
if(NULL!=itr && itr->Valid())
{
if (PREFETCH==action && m_Itr->m_Wrap.m_PrefetchStarted)
m_ResubmitWork=true;
// erlang is waiting, send message
if(m_Itr->keys_only)
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_Itr->m_Wrap.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_Itr->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
/**
* CloseTask functions
*/
CloseTask::CloseTask(ErlNifEnv* _owner_env, ERL_NIF_TERM _caller_ref,
DbObjectPtr_t & _db_handle)
: WorkTask(_owner_env, _caller_ref, _db_handle)
{}
CloseTask::~CloseTask()
{
}
work_result
CloseTask::DoWork()
{
DbObject * db_ptr;
// get db pointer then clear reference count to it
db_ptr=m_DbPtr.get();
m_DbPtr.assign(NULL);
if (NULL!=db_ptr)
{
// set closing flag, this is blocking
db_ptr->InitiateCloseRequest();
// db_ptr no longer valid
db_ptr=NULL;
return(work_result(ATOM_OK));
} // if
else
{
return work_result(local_env(), ATOM_ERROR, ATOM_BADARG);
} // else
}
/**
* ItrCloseTask functions
*/
ItrCloseTask::ItrCloseTask(ErlNifEnv* _owner_env, ERL_NIF_TERM _caller_ref,
ItrObjectPtr_t & _itr_handle)
: WorkTask(_owner_env, _caller_ref),
m_ItrPtr(_itr_handle)
{}
ItrCloseTask::~ItrCloseTask()
{
}
work_result
ItrCloseTask::DoWork()
{
ItrObject * itr_ptr;
// get iterator pointer then clear reference count to it
itr_ptr=m_ItrPtr.get();
m_ItrPtr.assign(NULL);
if (NULL!=itr_ptr)
{
// set closing flag, this is blocking
itr_ptr->InitiateCloseRequest();
// itr_ptr no longer valid
itr_ptr=NULL;
return(work_result(ATOM_OK));
} // if
else
{
return work_result(local_env(), ATOM_ERROR, ATOM_BADARG);
} // else
}
/**
* 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