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sortix--sortix/kernel/ptable.cpp

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/*
* Copyright (c) 2014 Jonas 'Sortie' Termansen.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* ptable.cpp
* Process table.
*/
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <sortix/kernel/kthread.h>
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#include <sortix/kernel/process.h>
#include <sortix/kernel/ptable.h>
#include <sortix/kernel/refcount.h>
// TODO: Process memory ownership needs to be reference counted.
// TODO: This implementation is rather run-time inefficient.
// TODO: The Free method potentially leaks memory as the ptable is never shrunk.
// TODO: The next_pid counter could potentially overflow.
namespace Sortix {
ProcessTable::ProcessTable()
{
ptablelock = KTHREAD_MUTEX_INITIALIZER;
next_pid = 0;
entries = NULL;
entries_used = 0;
entries_length = 0;
}
ProcessTable::~ProcessTable()
{
delete[] entries;
}
Process* ProcessTable::Get(pid_t pid)
{
ScopedLock lock(&ptablelock);
for ( size_t i = 0; i < entries_used; i++ )
if ( entries[i].pid == pid )
return entries[i].process;
return errno = ESRCH, (Process*) NULL;
}
pid_t ProcessTable::Allocate(Process* process)
{
ScopedLock lock(&ptablelock);
if ( entries_used == entries_length )
{
size_t new_length = entries_length ? 2 * entries_length : 64;
struct ptable_entry* new_entries = new struct ptable_entry[new_length];
if ( !new_entries )
return -1;
if ( entries )
{
size_t old_size = sizeof(struct ptable_entry) * entries_length;
memcpy(new_entries, entries, old_size);
delete[] entries;
}
entries = new_entries;
entries_length = new_length;
}
struct ptable_entry* entry = &entries[entries_used++];
entry->process = process;
return entry->pid = next_pid++;
}
void ProcessTable::Free(pid_t pid)
{
ScopedLock lock(&ptablelock);
for ( size_t i = 0; i < entries_used; i++ )
{
if ( entries[i].pid != pid )
continue;
entries[i] = entries[--entries_used];
return;
}
assert(false);
}
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pid_t ProcessTable::Prev(pid_t pid)
{
ScopedLock lock(&ptablelock);
pid_t result = -1;
for ( size_t i = 0; i < entries_used; i++ )
{
if ( pid <= entries[i].process->pid )
continue;
if ( result == -1 || result < entries[i].process->pid )
result = entries[i].process->pid;
}
return result;
}
pid_t ProcessTable::Next(pid_t pid)
{
ScopedLock lock(&ptablelock);
pid_t result = -1;
for ( size_t i = 0; i < entries_used; i++ )
{
if ( entries[i].process->pid <= pid )
continue;
if ( result == -1 || entries[i].process->pid < result )
result = entries[i].process->pid;
}
return result;
}
} // namespace Sortix