/* ccapi/server/ccs_lock_state.c */
/*
* Copyright 2006, 2007 Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "ccs_common.h"
struct ccs_lock_state_d {
cc_int32 invalid_object_err;
cc_int32 pending_lock_err;
cc_int32 no_lock_err;
ccs_lock_array_t locks;
cc_uint64 first_pending_lock_index;
};
struct ccs_lock_state_d ccs_lock_state_initializer = { 1, 1, 1, NULL, 0 };
/* ------------------------------------------------------------------------ */
cc_int32 ccs_lock_state_new (ccs_lock_state_t *out_lock_state,
cc_int32 in_invalid_object_err,
cc_int32 in_pending_lock_err,
cc_int32 in_no_lock_err)
{
cc_int32 err = ccNoError;
ccs_lock_state_t lock_state = NULL;
if (!out_lock_state) { err = cci_check_error (ccErrBadParam); }
if (!err) {
lock_state = malloc (sizeof (*lock_state));
if (lock_state) {
*lock_state = ccs_lock_state_initializer;
} else {
err = cci_check_error (ccErrNoMem);
}
}
if (!err) {
err = ccs_lock_array_new (&lock_state->locks);
}
if (!err) {
lock_state->invalid_object_err = in_invalid_object_err;
lock_state->pending_lock_err = in_pending_lock_err;
lock_state->no_lock_err = in_no_lock_err;
*out_lock_state = lock_state;
lock_state = NULL;
}
ccs_lock_state_release (lock_state);
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
cc_int32 ccs_lock_state_release (ccs_lock_state_t io_lock_state)
{
cc_int32 err = ccNoError;
if (!err && io_lock_state) {
ccs_lock_array_release (io_lock_state->locks);
free (io_lock_state);
}
return cci_check_error (err);
}
#ifdef TARGET_OS_MAC
#pragma mark -
#endif
/* ------------------------------------------------------------------------ */
static cc_int32 ccs_lock_status_add_pending_lock (ccs_lock_state_t io_lock_state,
ccs_pipe_t in_client_pipe,
ccs_pipe_t in_reply_pipe,
cc_uint32 in_lock_type,
cc_uint64 *out_lock_index)
{
cc_int32 err = ccNoError;
ccs_lock_t lock = NULL;
if (!io_lock_state ) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_client_pipe)) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_reply_pipe) ) { err = cci_check_error (ccErrBadParam); }
if (!err) {
err = ccs_lock_new (&lock, in_lock_type,
io_lock_state->invalid_object_err,
in_client_pipe, in_reply_pipe,
io_lock_state);
}
if (!err) {
err = ccs_lock_array_insert (io_lock_state->locks, lock,
ccs_lock_array_count (io_lock_state->locks));
if (!err) { lock = NULL; /* take ownership */ }
}
if (!err) {
*out_lock_index = ccs_lock_array_count (io_lock_state->locks) - 1;
}
ccs_lock_release (lock);
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
static cc_int32 ccs_lock_status_remove_lock (ccs_lock_state_t io_lock_state,
cc_uint64 in_lock_index)
{
cc_int32 err = ccNoError;
if (!io_lock_state) { err = cci_check_error (ccErrBadParam); }
if (!err) {
err = ccs_lock_array_remove (io_lock_state->locks, in_lock_index);
if (!err && in_lock_index < io_lock_state->first_pending_lock_index) {
io_lock_state->first_pending_lock_index--;
}
}
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
static cc_int32 ccs_lock_status_grant_lock (ccs_lock_state_t io_lock_state,
cc_uint64 in_pending_lock_index)
{
cc_int32 err = ccNoError;
ccs_lock_t pending_lock = NULL;
cc_uint32 type = 0;
if (!io_lock_state) { err = cci_check_error (ccErrBadParam); }
if (!err) {
pending_lock = ccs_lock_array_object_at_index (io_lock_state->locks,
in_pending_lock_index);
if (!pending_lock || in_pending_lock_index < io_lock_state->first_pending_lock_index) {
err = cci_check_error (ccErrBadParam);
}
}
if (!err) {
err = ccs_lock_type (pending_lock, &type);
}
if (!err && (type == cc_lock_upgrade || type == cc_lock_downgrade)) {
/* lock upgrades or downgrades. Find the old lock and remove it. */
ccs_pipe_t pending_client_pipe = CCS_PIPE_NULL;
err = ccs_lock_client_pipe (pending_lock, &pending_client_pipe);
if (!err) {
cc_uint64 i;
for (i = 0; !err && i < io_lock_state->first_pending_lock_index; i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
cc_uint32 is_lock_for_client = 0;
err = ccs_lock_is_for_client_pipe (lock, pending_client_pipe, &is_lock_for_client);
if (!err && is_lock_for_client) {
cci_debug_printf ("%s: Removing old lock %p at index %d to replace with pending lock %p.",
__FUNCTION__, lock, (int) i, pending_lock);
err = ccs_lock_status_remove_lock (io_lock_state, i);
if (!err) { i--; in_pending_lock_index--; /* We removed one so back up an index */ }
break;
}
}
}
}
if (!err) {
cc_uint64 new_lock_index = 0;
err = ccs_lock_array_move (io_lock_state->locks,
in_pending_lock_index,
io_lock_state->first_pending_lock_index,
&new_lock_index);
if (!err) { io_lock_state->first_pending_lock_index++; }
}
if (!err) {
err = ccs_lock_grant_lock (pending_lock);
}
return cci_check_error (err);
}
#ifdef TARGET_OS_MAC
#pragma mark -
#endif
/* ------------------------------------------------------------------------ */
static cc_int32 ccs_lock_state_check_pending_lock (ccs_lock_state_t io_lock_state,
ccs_pipe_t in_pending_lock_client_pipe,
cc_uint32 in_pending_lock_type,
cc_uint32 *out_grant_lock)
{
cc_int32 err = ccNoError;
cc_uint32 is_write_locked = 0;
cc_uint32 client_has_lock = 0;
cc_uint32 other_clients_have_locks = 0;
cc_uint32 client_lock_type = 0;
cc_uint64 client_lock_index = 0;
cc_uint32 grant_lock = 0;
if (!io_lock_state ) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_pending_lock_client_pipe)) { err = cci_check_error (ccErrBadParam); }
if (!out_grant_lock ) { err = cci_check_error (ccErrBadParam); }
if (!err) {
cc_uint64 i;
cc_uint64 lock_count = io_lock_state->first_pending_lock_index;
for (i = 0; !err && i < lock_count; i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
cc_uint32 lock_type = 0;
cc_uint32 lock_is_for_client = 0;
err = ccs_lock_type (lock, &lock_type);
if (!err) {
err = ccs_lock_is_for_client_pipe (lock, in_pending_lock_client_pipe,
&lock_is_for_client);
}
if (!err) {
if (lock_type == cc_lock_write || lock_type == cc_lock_upgrade) {
is_write_locked = 1;
}
if (!lock_is_for_client) {
other_clients_have_locks = 1;
} else if (!client_has_lock) { /* only record type of 1st lock */
client_has_lock = 1;
client_lock_type = lock_type;
client_lock_index = i;
}
}
}
}
if (!err) {
cc_uint64 lock_count = io_lock_state->first_pending_lock_index;
if (in_pending_lock_type == cc_lock_write) {
if (client_has_lock) {
err = cci_check_error (ccErrBadLockType);
} else {
grant_lock = (lock_count == 0);
}
} else if (in_pending_lock_type == cc_lock_read) {
if (client_has_lock) {
err = cci_check_error (ccErrBadLockType);
} else {
grant_lock = !is_write_locked;
}
} else if (in_pending_lock_type == cc_lock_upgrade) {
if (!client_has_lock || (client_lock_type != cc_lock_read &&
client_lock_type != cc_lock_downgrade)) {
err = cci_check_error (ccErrBadLockType);
} else {
/* don't grant if other clients have read locks */
grant_lock = !other_clients_have_locks;
}
} else if (in_pending_lock_type == cc_lock_downgrade) {
if (!client_has_lock || (client_lock_type != cc_lock_write &&
client_lock_type != cc_lock_upgrade)) {
err = cci_check_error (ccErrBadLockType);
} else {
/* downgrades can never block */
grant_lock = 1;
}
} else {
err = cci_check_error (ccErrBadLockType);
}
}
if (!err) {
*out_grant_lock = grant_lock;
}
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
static cc_int32 ccs_lock_status_try_to_grant_pending_locks (ccs_lock_state_t io_lock_state)
{
cc_int32 err = ccNoError;
cc_uint32 done = 0;
if (!io_lock_state) { err = cci_check_error (ccErrBadParam); }
/* Look at the pending locks and see if we can grant them.
* Note that downgrade locks mean we must check all pending locks each pass
* since a downgrade lock might be last in the list. */
while (!err && !done) {
cc_uint64 i;
cc_uint64 count = ccs_lock_array_count (io_lock_state->locks);
cc_uint32 granted_lock = 0;
for (i = io_lock_state->first_pending_lock_index; !err && i < count; i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
cc_uint32 lock_type = 0;
ccs_pipe_t client_pipe = CCS_PIPE_NULL;
cc_uint32 can_grant_lock_now = 0;
err = ccs_lock_client_pipe (lock, &client_pipe);
if (!err) {
err = ccs_lock_type (lock, &lock_type);
}
if (!err) {
err = ccs_lock_state_check_pending_lock (io_lock_state, client_pipe,
lock_type, &can_grant_lock_now);
}
if (!err && can_grant_lock_now) {
err = ccs_lock_status_grant_lock (io_lock_state, i);
if (!err) { granted_lock = 1; }
}
}
if (!err && !granted_lock) {
/* we walked over all the locks and couldn't grant any of them */
done = 1;
}
}
return cci_check_error (err);
}
#ifdef TARGET_OS_MAC
#pragma mark -
#endif
/* ------------------------------------------------------------------------ */
cc_int32 ccs_lock_state_add (ccs_lock_state_t io_lock_state,
ccs_pipe_t in_client_pipe,
ccs_pipe_t in_reply_pipe,
cc_uint32 in_lock_type,
cc_uint32 in_block,
cc_uint32 *out_will_send_reply)
{
cc_int32 err = ccNoError;
cc_uint32 can_grant_lock_now = 0;
if (!io_lock_state ) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_client_pipe)) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_reply_pipe) ) { err = cci_check_error (ccErrBadParam); }
if (!out_will_send_reply ) { err = cci_check_error (ccErrBadParam); }
if (!err) {
/* Sanity check: if there are any pending locks for this client
* the client must have timed out waiting for our reply. Remove any
* existing pending locks for the client. */
cc_uint64 i;
for (i = io_lock_state->first_pending_lock_index; !err && i < ccs_lock_array_count (io_lock_state->locks); i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
cc_uint32 has_pending_lock_for_client = 0;
err = ccs_lock_is_for_client_pipe (lock, in_client_pipe, &has_pending_lock_for_client);
if (!err && has_pending_lock_for_client) {
cci_debug_printf ("WARNING %s: Removing unexpected pending lock %p at index %d.",
__FUNCTION__, lock, (int) i);
err = ccs_lock_status_remove_lock (io_lock_state, i);
if (!err) { i--; /* We removed one so back up an index */ }
}
}
}
if (!err) {
err = ccs_lock_state_check_pending_lock (io_lock_state, in_client_pipe,
in_lock_type, &can_grant_lock_now);
}
if (!err) {
if (!can_grant_lock_now && (in_block == cc_lock_noblock)) {
err = cci_check_error (io_lock_state->pending_lock_err);
} else {
cc_uint64 new_lock_index = 0;
err = ccs_lock_status_add_pending_lock (io_lock_state,
in_client_pipe,
in_reply_pipe,
in_lock_type,
&new_lock_index);
if (!err && can_grant_lock_now) {
err = ccs_lock_status_grant_lock (io_lock_state, new_lock_index);
if (!err && (in_lock_type == cc_lock_downgrade)) {
/* downgrades can allow us to grant other locks */
err = ccs_lock_status_try_to_grant_pending_locks (io_lock_state);
}
}
}
}
if (!err) {
/* ccs_lock_state_add sends its replies via callback so caller shouldn't */
*out_will_send_reply = 1;
}
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
cc_int32 ccs_lock_state_remove (ccs_lock_state_t io_lock_state,
ccs_pipe_t in_client_pipe)
{
cc_int32 err = ccNoError;
cc_uint32 found_lock = 0;
if (!io_lock_state ) { err = cci_check_error (ccErrBadParam); }
if (!ccs_pipe_valid (in_client_pipe)) { err = cci_check_error (ccErrBadParam); }
if (!err) {
cc_uint64 i;
/* Remove all locks for this client.
* There should only be one so warn if there are multiple */
for (i = 0; !err && i < io_lock_state->first_pending_lock_index; i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
cc_uint32 is_for_client = 0;
err = ccs_lock_is_for_client_pipe (lock, in_client_pipe, &is_for_client);
if (!err && is_for_client) {
if (found_lock) {
cci_debug_printf ("WARNING %s: Found multiple locks for client.",
__FUNCTION__);
}
found_lock = 1;
cci_debug_printf ("%s: Removing lock %p at index %d.", __FUNCTION__, lock, (int) i);
err = ccs_lock_status_remove_lock (io_lock_state, i);
if (!err) { i--; /* We removed one so back up an index */ }
}
}
}
if (!err && !found_lock) {
err = cci_check_error (io_lock_state->no_lock_err);
}
if (!err) {
err = ccs_lock_status_try_to_grant_pending_locks (io_lock_state);
}
return cci_check_error (err);
}
/* ------------------------------------------------------------------------ */
cc_int32 ccs_lock_state_invalidate_lock (ccs_lock_state_t io_lock_state,
ccs_lock_t in_lock)
{
cc_int32 err = ccNoError;
if (!io_lock_state) { err = ccErrBadParam; }
if (!err) {
cc_uint64 i;
cc_uint64 count = ccs_lock_array_count (io_lock_state->locks);
for (i = 0; !err && i < count; i++) {
ccs_lock_t lock = ccs_lock_array_object_at_index (io_lock_state->locks, i);
if (lock == in_lock) {
err = ccs_lock_status_remove_lock (io_lock_state, i);
if (!err) {
err = ccs_lock_status_try_to_grant_pending_locks (io_lock_state);
break;
}
}
}
}
return cci_check_error (err);
}