water 0.3.9-alpha

A Rust library that provides a thread-safe distributed message sending facility supporting synchronous and asynchronous I/O.
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use std::rt::heap::allocate;
use std::rt::heap::deallocate;
use std::mem::size_of;
use std::sync::Mutex;
use std::intrinsics::transmute;
use std::mem::transmute_copy;
use std::mem::uninitialized;
use std::intrinsics::copy_memory;

// This is used to signify that a type is safe to
// be written and read from a RawMessage across
// process and machine boundaries. This trait can
// create dangerous code.
pub trait NoPointers { }

pub struct RawMessage {
    pub srcsid:     u64,             // source server id
    pub srceid:     u64,             // source endpoint id
    pub dstsid:     u64,             // destination server id
    pub dsteid:     u64,             // destination endpoint id
    buf:            *mut u8,         // message buffer
    len:            uint,            // specified buffer length
    cap:            uint,            // message buffer length
    refcnt:         *mut uint,       // reference count
    lock:           *mut Mutex<bool>,// 
}

impl Drop for RawMessage {
    fn drop(&mut self) {
        unsafe { 
            let lock = (*self.lock).lock();

            //println!("drop called for {:p} with ref cnt {}", self, *self.refcnt);
            if *self.refcnt < 1 {
                panic!("drop called for {:p} with reference count {} and buf {}!", self, *self.refcnt, self.buf);
            } 

            *self.refcnt = *self.refcnt - 1;

            if *self.refcnt < 1 {
                if self.cap > 0 {
                    deallocate(self.buf, self.cap, size_of::<uint>());
                    deallocate(self.lock as *mut u8, size_of::<Mutex<bool>>(), size_of::<uint>());
                    self.buf = 0 as *mut u8;
                    self.lock = 0 as *mut Mutex<bool>;
                }
            }
        }
    }
}

impl Clone for RawMessage {
    fn clone(&self) -> RawMessage {
        let lock = unsafe { (*self.lock).lock() };

        unsafe {
            *self.refcnt += 1;
        }

        RawMessage {
            srcsid: self.srcsid, srceid: self.srceid,
            dstsid: self.dstsid, dsteid: self.dsteid,
            buf: self.buf,
            cap: self.cap,
            len: self.len,
            refcnt: self.refcnt,
            lock: self.lock,
        }
    }
}

impl RawMessage {
    pub fn new(cap: uint) -> RawMessage {
        unsafe {
            let refcnt: *mut uint = allocate(size_of::<uint>(), size_of::<uint>()) as *mut uint;
            *refcnt = 1;

            let lock: *mut Mutex<bool> = allocate(size_of::<Mutex<bool>>(), size_of::<uint>()) as *mut Mutex<bool>;
            *lock = Mutex::new(false);

            RawMessage {
                srcsid: 0, srceid: 0, dstsid: 0, dsteid: 0,
                buf: allocate(cap, size_of::<uint>()),
                len: cap,
                cap: cap,
                refcnt: refcnt,
                lock: lock, 
            }
        }
    }

    pub fn new_fromstr(s: &str) -> RawMessage {
        let m = RawMessage::new(s.len());
        unsafe {
            copy_memory(m.buf, *(transmute::<&&str, *const uint>(&s)) as *const u8, s.len());
        }
        m
    }

    pub fn cap(&self) -> uint {
        let lock = unsafe { (*self.lock).lock() };
        return self.cap;
    }

    pub fn len(&self) -> uint {
        let lock = unsafe { (*self.lock).lock() };
        return self.len;
    }

    pub fn dup(&self) -> RawMessage {
        unsafe {
            let lock = (*self.lock).lock();

            let n = RawMessage::new(self.cap);
            copy_memory(n.buf, self.buf as *const u8, self.cap);

            n
        }
    }

    pub fn resize(&mut self, newcap: uint) {
        unsafe {
            let lock = (*self.lock).lock();

            if newcap == 0 {
                return;
            }

            let nbuf: *mut u8 = allocate(newcap, size_of::<uint>());
            
            if newcap < self.len {
                copy_memory(nbuf, self.buf as *const u8, newcap);
            } else {
                copy_memory(nbuf, self.buf as *const u8, self.cap);
            }

            deallocate(self.buf, self.cap, size_of::<uint>());
            self.buf = nbuf;

            self.cap = newcap;

            if self.len > self.cap {
                self.len = self.cap;
            }
        }
    }

    pub fn writestructref<T>(&mut self, offset: uint, t: &T) {
        let lock = unsafe { (*self.lock).lock() };

        if offset + size_of::<T>() > self.len {
            panic!("write past end of buffer!")
        }

        unsafe { copy_memory((self.buf as uint + offset) as *mut u8, transmute(t), size_of::<T>()); }        
    }

    pub fn writestruct<T>(&mut self, offset: uint, t: T) {
        let lock = unsafe { (*self.lock).lock() };

        if offset + size_of::<T>() > self.len {
            panic!("write past end of buffer!")
        }

        unsafe { copy_memory((self.buf as uint + offset) as *mut u8, transmute(&t), size_of::<T>()); }
    }

    pub fn readstruct<T: NoPointers>(&self, offset: uint) -> T {
        unsafe { self.readstructunsafe(offset) }
    }

    pub unsafe fn readstructunsafe<T>(&self, offset: uint) -> T {
        let mut out: T = uninitialized::<T>();

        if offset + size_of::<T>() > self.len {
            panic!("read past end of buffer!")
        }

        // Yeah, I had a little brain fart and things got out of hand here. I think
        // copy_memory's count argument is the multiple of size_of::<T>. So I ended
        // up doing u8, but maybe one day make this look more pretty.
        let ptr: *mut u8 = transmute_copy(&&out);
        copy_memory(ptr, (self.buf as uint + offset) as *const u8, size_of::<T>());

        out
    }

    pub unsafe fn readstructref<T>(&self, offset: uint, t: &mut T) {
        if offset + size_of::<T>() > self.len {
            panic!("read past end of buffer!")
        }

        copy_memory(t, (self.buf as uint + offset) as *const T, size_of::<T>());
    }

    pub fn writeu8(&mut self, offset: uint, value: u8) { self.writestruct(offset, value); }
    pub fn writeu16(&mut self, offset: uint, value: u16) { self.writestruct(offset, value); }
    pub fn writeu32(&mut self, offset: uint, value: u32) { self.writestruct(offset, value); }
    pub fn writei8(&mut self, offset: uint, value: i8) { self.writestruct(offset, value); }
    pub fn writei16(&mut self, offset: uint, value: i16) { self.writestruct(offset, value); }
    pub fn writei32(&mut self, offset: uint, value: i32) { self.writestruct(offset, value); }
    pub fn readu8(&self, offset: uint) -> u8 { unsafe { self.readstructunsafe(offset) } }
    pub fn readu16(&self, offset: uint) -> u16 { unsafe { self.readstructunsafe(offset) } }
    pub fn readu32(&self, offset: uint) -> u32 { unsafe { self.readstructunsafe(offset) } }
    pub fn readi8(&self, offset: uint) -> i8 { unsafe { self.readstructunsafe(offset) } }
    pub fn readi16(&self, offset: uint) -> i16 { unsafe { self.readstructunsafe(offset) } }
    pub fn readi32(&self, offset: uint) -> i32 { unsafe { self.readstructunsafe(offset) } }
}