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Implement a basic way for read() to block.

FileHandle gets a hasDataAvailableForRead() getter.
If this returns true in sys$read(), the task will block(BlockedRead) + yield.
The fd blocked on is stored in Task::m_fdBlockedOnRead.
The scheduler then looks at the state of that fd during the unblock phase.

This makes "sh" restful. :^)

There's still some problem with the kernel not surviving the colonel task
getting scheduled. I need to figure that out and fix it.
This commit is contained in:
Andreas Kling 2018-10-25 13:07:59 +02:00
parent ba56f4afde
commit c6f2890d8e
18 changed files with 86 additions and 17 deletions

View file

@ -21,6 +21,11 @@ Console::~Console()
{
}
bool Console::hasDataAvailableForRead() const
{
return false;
}
ssize_t Console::read(byte* buffer, size_t bufferSize)
{
// FIXME: Implement reading from the console.

View file

@ -9,6 +9,7 @@ public:
Console();
virtual ~Console() override;
virtual bool hasDataAvailableForRead() const override;
virtual ssize_t read(byte* buffer, size_t size) override;
virtual ssize_t write(const byte* data, size_t size) override;

View file

@ -86,6 +86,11 @@ Keyboard::~Keyboard()
ASSERT_NOT_REACHED();
}
bool Keyboard::hasDataAvailableForRead() const
{
return !m_queue.isEmpty();
}
ssize_t Keyboard::read(byte* buffer, size_t size)
{
ssize_t nread = 0;

View file

@ -18,6 +18,7 @@ private:
// ^CharacterDevice
virtual ssize_t read(byte* buffer, size_t) override;
virtual ssize_t write(const byte* buffer, size_t) override;
virtual bool hasDataAvailableForRead() const override;
CircularQueue<byte, 16> m_queue;
byte m_modifiers { 0 };

View file

@ -466,6 +466,14 @@ bool scheduleNewTask()
continue;
}
}
if (task->state() == Task::BlockedRead) {
ASSERT(task->m_fdBlockedOnRead != -1);
if (task->m_fileHandles[task->m_fdBlockedOnRead]->hasDataAvailableForRead()) {
task->unblock();
continue;
}
}
}
#if 0
@ -619,6 +627,13 @@ ssize_t Task::sys$read(int fd, void* outbuf, size_t nread)
#ifdef DEBUG_IO
kprintf("call read on handle=%p\n", handle);
#endif
if (handle->isBlocking()) {
if (!handle->hasDataAvailableForRead()) {
m_fdBlockedOnRead = fd;
block(BlockedRead);
yield();
}
}
nread = handle->read((byte*)outbuf, nread);
#ifdef DEBUG_IO
kprintf("Task::sys$read: nread=%u\n", nread);

View file

@ -31,11 +31,12 @@ public:
Invalid = 0,
Runnable = 1,
Running = 2,
BlockedSleep = 3,
BlockedWait = 4,
Terminated = 5,
Crashing = 6,
Exiting = 7,
Terminated = 3,
Crashing = 4,
Exiting = 5,
BlockedSleep = 6,
BlockedWait = 7,
BlockedRead = 8,
};
enum RingLevel {
@ -114,6 +115,7 @@ public:
private:
friend class MemoryManager;
friend bool scheduleNewTask();
Task(String&& name, uid_t, gid_t, pid_t parentPID, RingLevel);
@ -143,6 +145,7 @@ private:
void* m_kernelStack { nullptr };
dword m_timesScheduled { 0 };
pid_t m_waitee { -1 };
int m_fdBlockedOnRead { -1 };
String m_cwd;

View file

@ -165,7 +165,7 @@ static void init_stage2()
#endif
for (;;) {
sleep(3600 * TICKS_PER_SECOND);
//sleep(3600 * TICKS_PER_SECOND);
asm("hlt");
}
}