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bdberl/c_src/bdberl_drv.c
Dave Smith aa3928b2c3 Re-enable transaction timeouts
2008-12-10 21:39:38 -07:00

970 lines
29 KiB
C
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/* -------------------------------------------------------------------
*
* bdberl: Berkeley DB Driver for Erlang
* Copyright (c) 2008 The Hive. All rights reserved.
*
* ------------------------------------------------------------------- */
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <time.h>
#include <fcntl.h>
#include "hive_hash.h"
#include "bdberl_drv.h"
#include "bin_helper.h"
/**
* Function prototypes
*/
static int open_database(const char* name, DBTYPE type, PortData* data, int* errno);
static int close_database(int dbref, PortData* data);
static void do_async_put(void* arg);
static void do_async_get(void* arg);
static void do_async_txnop(void* arg);
static int add_dbref(PortData* data, int dbref);
static int del_dbref(PortData* data, int dbref);
static int has_dbref(PortData* data, int dbref);
static int add_portref(int dbref, ErlDrvPort port);
static int del_portref(int dbref, ErlDrvPort port);
static int alloc_dbref();
static void* zalloc(unsigned int size);
static void signal_port(PortData* d);
static void* deadlock_check(void* arg);
/**
* Global instance of DB_ENV; only a single one exists per O/S process.
*/
static DB_ENV* G_DB_ENV;
/**
* Global variable to track the return code from opening the DB_ENV. We track this
* value so as to provide a useful error code when the user attempts to open the
* port and it fails due to an error that occurred when opening the environment.
*/
static int G_DB_ENV_ERROR;
/**
* G_DATABASES is a global array of Database structs. Used to track currently opened DB*
* handles and ensure that they get cleaned up when all ports which were using them exit or
* explicitly close them.
*
* This array is allocated when the driver is first initialized and does not grow/shrink
* dynamically. G_DATABASES_SIZE contains the size of the array. G_DATABASES_NAMES is a hash of
* filenames to array index for an opened Database.
*
* All access to G_DATABASES and G_DATABASES_NAMES must be protected by the read/write lock
* G_DATABASES_RWLOCK.
*/
static Database* G_DATABASES;
static int G_DATABASES_SIZE;
static ErlDrvRWLock* G_DATABASES_RWLOCK;
static hive_hash* G_DATABASES_NAMES;
/**
* G_DEADLOCK_* a
*/
static ErlDrvTid G_DEADLOCK_THREAD;
static unsigned int G_DEADLOCK_CHECK_ACTIVE = 1;
static unsigned int G_DEADLOCK_CHECK_INTERVAL = 100;
/**
*
*/
static TPool* G_TPOOL_GENERAL;
static TPool* G_TPOOL_TXNS;
/**
* Helpful macros
*/
#define READ_LOCK(L) erl_drv_rwlock_rlock(L)
#define READ_UNLOCK(L) erl_drv_rwlock_runlock(L)
#define PROMOTE_READ_LOCK(L) erl_drv_rwlock_runlock(L); erl_drv_rwlock_rwlock(L)
#define WRITE_LOCK(L) erl_drv_rwlock_rwlock(L)
#define WRITE_UNLOCK(L) erl_drv_rwlock_rwunlock(L)
#define RETURN_BH(bh, outbuf) *outbuf = (char*)bh.bin; return bh.bin->orig_size;
#define RETURN_INT(val, outbuf) { \
BinHelper bh; \
bin_helper_init(&bh, 4); \
bin_helper_push_int32(&bh, val); \
RETURN_BH(bh, outbuf); }
DRIVER_INIT(bdberl_drv)
{
printf("DRIVER INIT\n");
// Setup flags we'll use to init the environment
int flags =
DB_INIT_LOCK | /* Enable support for locking */
DB_INIT_TXN | /* Enable support for transactions */
DB_INIT_MPOOL | /* Enable support for memory pools */
DB_RECOVER | /* Enable support for recovering from failures */
DB_CREATE | /* Create files as necessary */
DB_REGISTER | /* Run recovery if needed */
DB_THREAD; /* Make the environment free-threaded */
// Initialize global environment -- use environment variable DB_HOME to
// specify where the working directory is
db_env_create(&G_DB_ENV, 0);
G_DB_ENV_ERROR = G_DB_ENV->open(G_DB_ENV, 0, flags, 0);
if (G_DB_ENV_ERROR == 0)
{
// Use the BDBERL_MAX_DBS environment value to determine the max # of
// databases to permit the VM to open at once. Defaults to 1024.
G_DATABASES_SIZE = 1024;
char* max_dbs_str = getenv("BDBERL_MAX_DBS"); /* TODO: Use erl_drv_getenv */
if (max_dbs_str != 0)
{
G_DATABASES_SIZE = atoi(max_dbs_str);
if (G_DATABASES_SIZE <= 0)
{
G_DATABASES_SIZE = 1024;
}
}
// Make sure we can distiguish between lock timeouts and deadlocks
int rc = G_DB_ENV->set_flags(G_DB_ENV, DB_TIME_NOTGRANTED, 1);
printf("TIME_NOT_GRANTED rc: %d\n", rc);
db_timeout_t to = 500 * 1000; // 500 ms
rc = G_DB_ENV->set_timeout(G_DB_ENV, to, DB_SET_TXN_TIMEOUT);
printf("DB_SET_TXN_TMEOUT rc: %d value %d\n", rc, to);
// BDB is setup -- allocate structures for tracking databases
G_DATABASES = (Database*) driver_alloc(sizeof(Database) * G_DATABASES_SIZE);
memset(G_DATABASES, '\0', sizeof(Database) * G_DATABASES_SIZE);
G_DATABASES_RWLOCK = erl_drv_rwlock_create("bdberl_drv: G_DATABASES_RWLOCK");
G_DATABASES_NAMES = hive_hash_new(G_DATABASES_SIZE);
// Startup deadlock check thread
erl_drv_thread_create("bdberl_drv_deadlock_checker", &G_DEADLOCK_THREAD,
&deadlock_check, 0, 0);
// Startup our thread pools
// TODO: Make configurable/adjustable
G_TPOOL_GENERAL = bdberl_tpool_start(5);
G_TPOOL_TXNS = bdberl_tpool_start(5);
}
else
{
// Something bad happened while initializing BDB; in this situation we
// cleanup and set the environment to zero. Attempts to open ports will
// fail and the user will have to sort out how to resolve the issue.
G_DB_ENV->close(G_DB_ENV, 0);
G_DB_ENV = 0;
}
return &bdberl_drv_entry;
}
static ErlDrvData bdberl_drv_start(ErlDrvPort port, char* buffer)
{
// Make sure we have a functional environment -- if we don't,
// bail...
if (!G_DB_ENV)
{
return ERL_DRV_ERROR_BADARG;
}
PortData* d = (PortData*)driver_alloc(sizeof(PortData));
memset(d, '\0', sizeof(PortData));
// Save handle to the port
d->port = port;
// Setup a pair of pipes for notification purposes
assert(pipe(d->pipe_fds) == 0);
// Make sure both pipes are configured non-blocking
assert(fcntl(d->pipe_fds[0], F_SETFL, O_NONBLOCK) == 0);
assert(fcntl(d->pipe_fds[1], F_SETFL, O_NONBLOCK) == 0);
// Make sure port is running in binary mode
set_port_control_flags(port, PORT_CONTROL_FLAG_BINARY);
return (ErlDrvData)d;
}
static void bdberl_drv_stop(ErlDrvData handle)
{
PortData* d = (PortData*)handle;
// printf("%p: stop\n", d->port);
// If there is an async job pending, we need to cancel it. The cancel operation will
// block until the job has either been removed or has run
if (d->async_job)
{
printf("Cancelling async job for port: %p\n", d->port);
bdberl_tpool_cancel(d->async_pool, d->async_job);
driver_select(d->port, (ErlDrvEvent)d->pipe_fds[0], DO_READ, 0);
printf("Canceled async job for port: %p\n", d->port);
}
// If a txn is currently active, terminate it. We _must_ do it synchronously (unfortunately) as
// there doesn't seem to be a to do an async op while stopping the driver.
if (d->txn)
{
d->txn->abort(d->txn);
}
// Close all the databases we previously opened
while (d->dbrefs)
{
close_database(d->dbrefs->dbref, d);
}
close(d->pipe_fds[0]);
close(d->pipe_fds[1]);
printf("Stopped port: %p\n", d->port);
// Release the port instance data
driver_free(handle);
}
static void bdberl_drv_finish()
{
// Stop the thread pools
bdberl_tpool_stop(G_TPOOL_GENERAL);
bdberl_tpool_stop(G_TPOOL_TXNS);
// Signal the deadlock checker to shutdown -- then wait for it
G_DEADLOCK_CHECK_ACTIVE = 0;
erl_drv_thread_join(G_DEADLOCK_THREAD, 0);
// Cleanup and shut down the BDB environment. Note that we assume
// all ports have been released and thuse all databases/txns/etc are also gone.
G_DB_ENV->close(G_DB_ENV, 0);
driver_free(G_DATABASES);
erl_drv_rwlock_destroy(G_DATABASES_RWLOCK);
hive_hash_destroy(G_DATABASES_NAMES);
printf("DRIVER_FINISH\n");
}
static int bdberl_drv_control(ErlDrvData handle, unsigned int cmd,
char* inbuf, int inbuf_sz,
char** outbuf, int outbuf_sz)
{
PortData* d = (PortData*)handle;
switch(cmd)
{
case CMD_OPEN_DB:
{
// Extract the type code and filename from the inbuf
// Inbuf is: <<Type:8, Name/bytes, 0:8>>
DBTYPE type = (DBTYPE)((char)*inbuf);
char* name = (char*)(inbuf+1);
int dbref;
int status;
int rc = open_database(name, type, d, &dbref);
if (rc == 0)
{
status = STATUS_OK;
}
else
{
status = STATUS_ERROR;
dbref = rc;
}
// Pack the status and dbref (or errno) into a binary and return it
// Outbuf is: <<Status:8, DbRef:32>>
BinHelper bh;
bin_helper_init(&bh, 5);
bin_helper_push_byte(&bh, status);
bin_helper_push_int32(&bh, dbref);
RETURN_BH(bh, outbuf);
}
case CMD_CLOSE_DB:
{
// TODO: If data is inflight, fail. Abort any open txns.
// Take the provided dbref and attempt to close it
int dbref = *((int*)inbuf);
int rc = close_database(dbref, d);
// Outbuf is: <<Rc:32>>
RETURN_INT(rc, outbuf);
}
case CMD_TXN_BEGIN:
{
// If an async operation is pending, fail
if (d->async_op != CMD_NONE)
{
RETURN_INT(ERROR_ASYNC_PENDING, outbuf);
}
// If we already have a txn open, fail
if (d->txn != 0)
{
RETURN_INT(ERROR_TXN_OPEN, outbuf);
}
// Outbuf is <<Rc:32>>
int rc = G_DB_ENV->txn_begin(G_DB_ENV, 0, &(d->txn), 0);
RETURN_INT(rc, outbuf);
}
case CMD_TXN_COMMIT:
case CMD_TXN_ABORT:
{
// If an async operation is pending, fail
if (d->async_op != CMD_NONE)
{
RETURN_INT(ERROR_ASYNC_PENDING, outbuf);
}
// If we don't already have a txn open, fail
if (d->txn == 0)
{
RETURN_INT(ERROR_NO_TXN, outbuf);
}
// Allocate operation structure
AsyncData* adata = zalloc(sizeof(AsyncData));
adata->port = d;
// Update port data to indicate we have an operation in progress
d->async_op = cmd;
// Schedule async operation to execute the commit/abort
d->async_data = adata;
d->async_pool = G_TPOOL_TXNS;
d->async_job = bdberl_tpool_run(G_TPOOL_TXNS, &do_async_txnop, adata, 0);
// Watch for events on the output pipe
// TODO: Can we do this just once ?!
driver_select(d->port, (ErlDrvEvent)d->pipe_fds[0], DO_READ, 1);
// Outbuf is <<Rc:32>>
RETURN_INT(0, outbuf);
}
case CMD_PUT:
case CMD_GET:
{
// If another async op is pending, fail
if (d->async_op != CMD_NONE)
{
RETURN_INT(ERROR_ASYNC_PENDING, outbuf);
}
// Inbuf is: << DbRef:32, Rest/binary>>
int dbref = *((int*)inbuf);
// Make sure this port currently has dbref open -- if it doesn't, error out. Of note,
// if it's in our list, we don't need to grab the RWLOCK, as we don't have to worry about
// the underlying handle disappearing since we have a reference.
if (has_dbref(d, dbref))
{
// Allocate operation structure
void* thread_data = zalloc(sizeof(AsyncData) + inbuf_sz);
AsyncData* adata = (AsyncData*)thread_data;
adata->port = d;
adata->db = G_DATABASES[dbref].db;
adata->payload = thread_data + sizeof(AsyncData);
// Copy the payload into place
memcpy(adata->payload, inbuf, inbuf_sz);
// Mark the port as busy and then schedule the appropriate async operation
d->async_op = cmd;
TPoolJobFunc fn;
if (cmd == CMD_PUT)
{
fn = &do_async_put;
}
else if (cmd == CMD_GET)
{
fn = &do_async_get;
}
d->async_data = adata;
d->async_pool = G_TPOOL_GENERAL;
d->async_job = bdberl_tpool_run(G_TPOOL_GENERAL, fn, adata, 0);
// Watch for events on the output pipe
// TODO: Can we do this just once ?!
driver_select(d->port, (ErlDrvEvent)d->pipe_fds[0], DO_READ, 1);
// Let caller know that the operation is in progress
// Outbuf is: <<0:32>>
RETURN_INT(0, outbuf);
}
else
{
// Invalid dbref
RETURN_INT(ERROR_INVALID_DBREF, outbuf);
}
}
}
*outbuf = 0;
return 0;
}
static void bdberl_drv_ready_input(ErlDrvData handle, ErlDrvEvent event)
{
PortData* d = (PortData*)handle;
// printf("%p: ready_input; cmd = %d; rc = %d\n", d->port, d->async_op,
// ((AsyncData*)d->async_data)->rc);
// Empty out the queue
int readbuf;
while (read((int)event, &readbuf, sizeof(readbuf)) > 0) { ; }
driver_select(d->port, event, DO_READ, 0);
// The async op has completed running on the thread pool -- process the results
switch (d->async_op)
{
case CMD_PUT:
case CMD_TXN_COMMIT:
case CMD_TXN_ABORT:
{
AsyncData* adata = (AsyncData*)d->async_data;
// Extract return code == if it's zero, send back "ok" to driver process; otherwise
// send a {error, Reason} tuple
if (adata->rc == 0)
{
ErlDrvTermData response[] = { ERL_DRV_ATOM, driver_mk_atom("ok") };
driver_output_term(d->port, response, sizeof(response) / sizeof(response[0]));
}
else
{
ErlDrvTermData response[] = { ERL_DRV_ATOM, driver_mk_atom("error"),
ERL_DRV_INT, adata->rc,
ERL_DRV_TUPLE, 2};
driver_output_term(d->port, response, sizeof(response) / sizeof(response[0]));
}
// If this was a commit/abort, or a deadlock occurred while in a transaction,
// clear out the handle -- it's already invalid
if (d->async_op == CMD_TXN_COMMIT || d->async_op == CMD_TXN_ABORT ||
(d->txn && (adata->rc == DB_LOCK_NOTGRANTED || adata->rc == DB_LOCK_DEADLOCK)))
{
d->txn = 0;
}
// Cleanup async data and mark the port as not busy
driver_free(d->async_data);
d->async_data = 0;
d->async_op = CMD_NONE;
d->async_job = 0;
d->async_pool = 0;
break;
}
case CMD_GET:
{
// Extract return code == if it's zero, send back {ok, Payload} or not_found to driver
// process; otherwise send a {error, Reason} tuple
AsyncData* adata = (AsyncData*)d->async_data;
if (adata->rc == 0)
{
ErlDrvTermData response[] = { ERL_DRV_ATOM, driver_mk_atom("ok"),
ERL_DRV_BUF2BINARY, (ErlDrvTermData)adata->payload, (ErlDrvUInt)adata->payload_sz,
ERL_DRV_TUPLE, 2};
driver_output_term(d->port, response, sizeof(response) / sizeof(response[0]));
}
else if (adata->rc == DB_NOTFOUND)
{
ErlDrvTermData response[] = { ERL_DRV_ATOM, driver_mk_atom("not_found") };
driver_output_term(d->port, response, sizeof(response) / sizeof(response[0]));
}
else
{
ErlDrvTermData response[] = { ERL_DRV_ATOM, driver_mk_atom("error"),
ERL_DRV_INT, adata->rc,
ERL_DRV_TUPLE, 2};
driver_output_term(d->port, response, sizeof(response) / sizeof(response[0]));
}
// If a deadlock occurred while in a transaction, clear out the handle -- it's
// already invalid
if (d->txn && (adata->rc == DB_LOCK_DEADLOCK || adata->rc == DB_LOCK_NOTGRANTED))
{
d->txn = 0;
}
// Cleanup async data and mark the port as not busy
driver_free(adata->payload);
driver_free(d->async_data);
d->async_data = 0;
d->async_op = CMD_NONE;
d->async_job = 0;
d->async_pool = 0;
break;
}
}
}
static int open_database(const char* name, DBTYPE type, PortData* data, int* dbref_res)
{
*dbref_res = -1;
READ_LOCK(G_DATABASES_RWLOCK);
// Look up the database by name in our hash table
Database* database = (Database*)hive_hash_get(G_DATABASES_NAMES, name);
if (database)
{
// Convert the database pointer into a dbref
int dbref = database - G_DATABASES;
// Great, the database was previously opened by someone else. Add it to our
// list of refs, and if it's a new addition also register this port with the
// Database structure in G_DATABASES
if (add_dbref(data, dbref))
{
// Need to update G_DATABASES -- grab the write lock
PROMOTE_READ_LOCK(G_DATABASES_RWLOCK);
// Add a reference to this port
add_portref(dbref, data->port);
// Release RW lock and return the ref
WRITE_UNLOCK(G_DATABASES_RWLOCK);
*dbref_res = dbref;
return 0;
}
else
{
// Already in our list of opened databases -- unlock and return the reference
READ_UNLOCK(G_DATABASES_RWLOCK);
*dbref_res = dbref;
return 0;
}
}
else
{
// This database hasn't been opened yet -- grab a write lock
PROMOTE_READ_LOCK(G_DATABASES_RWLOCK);
// While waiting on the write lock, another thread could have slipped in and
// opened the database, so do one more check to see if the database is already
// open
database = (Database*)hive_hash_get(G_DATABASES_NAMES, name);
if (database)
{
// Database got created while we were waiting on the write lock, add a reference
// to our port and drop the lock ASAP
int dbref = database - G_DATABASES;
add_portref(dbref, data->port);
WRITE_UNLOCK(G_DATABASES_RWLOCK);
add_dbref(data, dbref);
*dbref_res = dbref;
return 0;
}
// Database hasn't been created while we were waiting on write lock, so
// create/open it
// Find the first available slot in G_DATABASES; the index will be our
// reference for database operations
int dbref = alloc_dbref();
if (dbref < 0)
{
// No more slots available
WRITE_UNLOCK(G_DATABASES_RWLOCK);
return ERROR_MAX_DBS;
}
// Create the DB handle
DB* db;
int rc = db_create(&db, G_DB_ENV, 0);
if (rc != 0)
{
// Failure while creating the database handle -- drop our lock and return
// the code
WRITE_UNLOCK(G_DATABASES_RWLOCK);
return rc;
}
// Attempt to open our database
rc = db->open(db, 0, name, 0, type, DB_CREATE | DB_AUTO_COMMIT | DB_THREAD, 0);
if (rc != 0)
{
// Failure while opening the database -- cleanup the handle, drop the lock
// and return
db->close(db, 0);
WRITE_UNLOCK(G_DATABASES_RWLOCK);
return rc;
}
// Database is open. Store all the data into the allocated ref
G_DATABASES[dbref].db = db;
G_DATABASES[dbref].name = strdup(name);
G_DATABASES[dbref].ports = zalloc(sizeof(PortList));
G_DATABASES[dbref].ports->port = data->port;
// Make entry in hash table of names
hive_hash_add(G_DATABASES_NAMES, G_DATABASES[dbref].name, &(G_DATABASES[dbref]));
// Drop the write lock
WRITE_UNLOCK(G_DATABASES_RWLOCK);
// Add the dbref to the port list
add_dbref(data, dbref);
*dbref_res = dbref;
return 0;
}
}
static int close_database(int dbref, PortData* data)
{
// printf("Closing %d for port %p\n", dbref, data->port);
// Remove this database from our list
if (del_dbref(data, dbref))
{
// Something was actually deleted from our list -- now we need to disassociate the
// calling port with the global database structure.
WRITE_LOCK(G_DATABASES_RWLOCK);
assert(G_DATABASES[dbref].db != 0);
assert(G_DATABASES[dbref].ports != 0);
// Now disassociate this port from the database's port list
del_portref(dbref, data->port);
// Finally, if there are no other references to the database, close out
// the database completely
Database* database = &G_DATABASES[dbref];
if (database->ports == 0)
{
printf("Closing actual database for dbref %d\n", dbref);
// Close out the BDB handle
database->db->close(database->db, 0);
// Remove the entry from the names map
hive_hash_remove(G_DATABASES_NAMES, database->name);
free((char*)database->name);
// Zero out the whole record
memset(database, '\0', sizeof(Database));
}
WRITE_UNLOCK(G_DATABASES_RWLOCK);
return 1;
}
return 0;
}
static void do_async_put(void* arg)
{
AsyncData* adata = (AsyncData*)arg;
// printf("%p: do_async_put\n", adata->port->port);
// Setup DBTs
DBT key;
DBT value;
memset(&key, '\0', sizeof(DBT));
memset(&value, '\0', sizeof(DBT));
// Parse payload into DBTs
// Payload is: << DbRef:32, KeyLen:32, Key:KeyLen, ValLen:32, Val:ValLen>>
key.size = *((int*)(adata->payload + 4));
key.data = (void*)(adata->payload + 8);
value.size = *((int*)(adata->payload + 8 + key.size));
value.data = (void*)(adata->payload + 8 + key.size + 4);
// Execute the actual put -- we'll process the result back in the driver_async_ready function
// All databases are opened with AUTO_COMMIT, so if msg->port->txn is NULL, the put will still
// be atomic
adata->rc = adata->db->put(adata->db, adata->port->txn, &key, &value, 0);
// If any error occurs while we have a txn action, abort it
if (adata->port->txn && adata->rc)
{
adata->port->txn->abort(adata->port->txn);
}
// Enqueue a signal for the port to know that the operation is complete
signal_port(adata->port);
}
static void do_async_get(void* arg)
{
AsyncData* adata = (AsyncData*)arg;
// printf("%p: do_async_get\n", adata->port->port);
// Setup DBTs
DBT key;
DBT value;
memset(&key, '\0', sizeof(DBT));
memset(&value, '\0', sizeof(DBT));
// Parse payload into DBT
// Payload is: << DbRef:32, KeyLen:32, Key:KeyLen >>
key.size = *((int*)(adata->payload + 4));
key.data = (void*)(adata->payload + 8);
// Allocate memory to hold the value -- hard code initial size to 4k
// TODO: Make this smarter!
value.data = zalloc(4096);
value.ulen = 4096;
value.flags = DB_DBT_USERMEM;
int rc = adata->db->get(adata->db, adata->port->txn, &key, &value, 0);
while (rc == DB_BUFFER_SMALL)
{
// Grow our value buffer and try again
value.data = driver_realloc(value.data, value.size);
value.ulen = value.size;
rc = adata->db->get(adata->db, adata->port->txn, &key, &value, 0);
}
adata->payload = value.data;
adata->payload_sz = value.size; // Not ulen -- we want the actual data size
adata->rc = rc;
// If any error occurs while we have a txn action, abort it
if (adata->rc != DB_NOTFOUND && adata->port->txn && adata->rc)
{
adata->port->txn->abort(adata->port->txn);
}
signal_port(adata->port);
}
static void do_async_txnop(void* arg)
{
AsyncData* adata = (AsyncData*)arg;
// printf("%p: do_async_txnop\n", adata->port->port);
// Execute the actual commit/abort
if (adata->port->async_op == CMD_TXN_COMMIT)
{
adata->rc = adata->port->txn->commit(adata->port->txn, 0);
}
else
{
adata->rc = adata->port->txn->abort(adata->port->txn);
}
signal_port(adata->port);
}
static void* zalloc(unsigned int size)
{
void* res = driver_alloc(size);
memset(res, '\0', size);
return res;
}
#define zfree(p) driver_free(p)
static int add_portref(int dbref, ErlDrvPort port)
{
PortList* current = G_DATABASES[dbref].ports;
if (current)
{
PortList* last = 0;
do
{
// If the current item matches our port, bail -- nothing to do here
if (current->port == port)
{
return 0;
}
last = current;
current = current->next;
} while (current != 0);
// At the end of the list -- allocate a new entry for this por
current = (PortList*)zalloc(sizeof(PortList));
current->port = port;
last->next = current;
return 1;
}
else
{
// Current was initially NULL, so alloc the first one and add it.
current = zalloc(sizeof(PortList));
current->port = port;
G_DATABASES[dbref].ports = current;
return 1;
}
}
static int del_portref(int dbref, ErlDrvPort port)
{
PortList* current = G_DATABASES[dbref].ports;
PortList* last = 0;
while (current)
{
if (current->port == port)
{
// Found our match -- look back and connect the last item to our next
if (last)
{
last->next = current->next;
}
else
{
G_DATABASES[dbref].ports = current->next;
}
// Delete this entry
zfree(current);
return 1;
}
last = current;
current = current->next;
}
// Didn't delete anything
return 0;
}
/**
* Add a db reference to a port's DbRefList. Returns 1 if added; 0 if already present
*/
static int add_dbref(PortData* data, int dbref)
{
DbRefList* current = data->dbrefs;
if (current)
{
DbRefList* last = 0;
do
{
if (current->dbref == dbref)
{
return 0;
}
last = current;
current = current->next;
} while (current != 0);
// At the end of the list -- allocate a new entry
current = zalloc(sizeof(DbRefList));
current->dbref = dbref;
last->next = current;
return 1;
}
else
{
// Current was initially NULL, so alloc the first one
current = zalloc(sizeof(DbRefList));
current->dbref = dbref;
data->dbrefs = current;
return 1;
}
}
/**
* Delete a db reference from a port's DbRefList. Returns 1 if deleted; 0 if not
*/
static int del_dbref(PortData* data, int dbref)
{
DbRefList* current = data->dbrefs;
DbRefList* last = 0;
while (current)
{
if (current->dbref == dbref)
{
// Found our match -- look back and connect the last item to our next
if (last)
{
last->next = current->next;
}
else
{
data->dbrefs = current->next;
}
// Delete this entry
zfree(current);
return 1;
}
last = current;
current = current->next;
}
// Didn't delete anything
return 0;
}
/**
* Validate that a provided dbref is currently opened by a port. Return 1 if true; 0 if false.
*/
static int has_dbref(PortData* data, int dbref)
{
DbRefList* current = data->dbrefs;
while (current)
{
if (current->dbref == dbref)
{
return 1;
}
current = current->next;
}
return 0;
}
/**
* Allocate a Database structure; find first available slot in G_DATABASES and return the
* index of it. If no free slots are available, return -1
*/
static int alloc_dbref()
{
int i;
for (i = 0; i < G_DATABASES_SIZE; i++)
{
if (G_DATABASES[i].db == 0)
{
return i;
}
}
return -1;
}
static void signal_port(PortData* d)
{
int flag = 1;
write(d->pipe_fds[1], &flag, sizeof(flag));
}
/**
* Thread function that runs the deadlock checker periodically
*/
static void* deadlock_check(void* arg)
{
while(G_DEADLOCK_CHECK_ACTIVE)
{
// Run the lock detection
int count = 0;
G_DB_ENV->lock_detect(G_DB_ENV, 0, DB_LOCK_DEFAULT, &count);
if (count > 0)
{
printf("Rejected deadlocks: %d\n", count);
}
// TODO: Use nanosleep
usleep(G_DEADLOCK_CHECK_INTERVAL * 1000);
}
printf("Deadlock checker exiting.\n");
return 0;
}
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