From 14e9b43f32efc3ed8d9b248e8193d9ce5fe3a744 Mon Sep 17 00:00:00 2001
From: ksherlock <ksherlock@aa027e90-d47c-11dd-86d7-074df07e0730>
Date: Sat, 19 Feb 2011 18:05:57 +0000
Subject: [PATCH] new branch to integrate BlockDevice, BlockCache

git-svn-id: https://profuse.googlecode.com/svn/branches/profuse_interim@331 aa027e90-d47c-11dd-86d7-074df07e0730
---
 Cache/BlockCache.cpp         |  73 +++++++
 Cache/BlockCache.h           |  61 ++++++
 Cache/ConcreteBlockCache.cpp | 375 +++++++++++++++++++++++++++++++++++
 Cache/ConcreteBlockCache.h   |  70 +++++++
 Cache/MappedBlockCache.cpp   | 134 +++++++++++++
 Cache/MappedBlockCache.h     |  35 ++++
 6 files changed, 748 insertions(+)
 create mode 100644 Cache/BlockCache.cpp
 create mode 100644 Cache/BlockCache.h
 create mode 100644 Cache/ConcreteBlockCache.cpp
 create mode 100644 Cache/ConcreteBlockCache.h
 create mode 100644 Cache/MappedBlockCache.cpp
 create mode 100644 Cache/MappedBlockCache.h

diff --git a/Cache/BlockCache.cpp b/Cache/BlockCache.cpp
new file mode 100644
index 0000000..b6670b5
--- /dev/null
+++ b/Cache/BlockCache.cpp
@@ -0,0 +1,73 @@
+
+#include <algorithm>
+#include <cerrno>
+#include <cstring>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+
+#include <Cache/BlockCache.h>
+#include <Device/BlockDevice.h>
+
+#include <ProFUSE/Exception.h>
+#include <ProFUSE/auto.h>
+
+
+
+
+using namespace Device;
+
+using ProFUSE::Exception;
+using ProFUSE::POSIXException;
+
+
+BlockCache::BlockCache(BlockDevice *device)
+{
+    _device = device;
+    _blocks = device->blocks();
+    _readOnly = device->readOnly();
+}
+
+BlockCache::~BlockCache()
+{
+    delete _device;
+}
+
+void BlockCache::write(unsigned block, const void *bp)
+{
+    void *address = acquire(block);
+    std::memcpy(address, bp, 512);
+    release(block, true);
+}
+
+void BlockCache::read(unsigned block, void *bp)
+{
+    void *address = acquire(block);
+    std::memcpy(bp, address, 512);
+    release(block, false);
+}
+
+
+BlockCache *BlockCache::Create(BlockDevice *device)
+{
+    if (!device) return NULL;
+    
+    return device->createBlockCache();
+}
+
+
+void BlockCache::zeroBlock(unsigned block)
+{
+    /*
+    void *address = acquire(block);
+    std::memset(address, 0, 512);
+    release(block, true);
+    */
+
+    uint8_t buffer[512];
+    
+    std::memset(buffer, 0, 512);
+    write(block, buffer);    
+}
diff --git a/Cache/BlockCache.h b/Cache/BlockCache.h
new file mode 100644
index 0000000..c4587d1
--- /dev/null
+++ b/Cache/BlockCache.h
@@ -0,0 +1,61 @@
+#ifndef __BLOCKCACHE_H__
+#define __BLOCKCACHE_H__
+
+#include <stdint.h>
+#include <vector>
+
+class MappedFile;
+
+namespace Device {
+
+class BlockDevice;
+
+enum BlockReleaseFlags {
+    kBlockDirty = 1,
+    kBlockCommitNow = 2,
+    kBlockReuse = 3
+};
+
+class BlockCache {
+public:
+
+    static BlockCache *Create(BlockDevice *device);
+
+    virtual ~BlockCache();
+
+    bool readOnly() { return _readOnly; }
+    unsigned blocks() { return _blocks; }
+    BlockDevice *device() { return _device; }
+    
+        
+    virtual void sync() = 0;
+    virtual void write(unsigned block, const void *bp);
+    virtual void read(unsigned block, void *bp);
+
+    virtual void *acquire(unsigned block) = 0;
+    virtual void release(unsigned block, int flags) = 0 ;
+    virtual void markDirty(unsigned block) = 0;
+    
+    
+    virtual void zeroBlock(unsigned block);
+    
+    void release(unsigned block) { release(block, 0); }
+    void release(unsigned block, bool dirty) 
+    {
+        release(block, dirty ? kBlockDirty : 0);
+    }
+
+protected:
+    BlockCache(BlockDevice *device);
+
+    BlockDevice *_device;
+    
+private:
+    unsigned _blocks;
+    bool _readOnly;
+};
+
+
+} // namespace
+
+#endif
diff --git a/Cache/ConcreteBlockCache.cpp b/Cache/ConcreteBlockCache.cpp
new file mode 100644
index 0000000..5e0bd69
--- /dev/null
+++ b/Cache/ConcreteBlockCache.cpp
@@ -0,0 +1,375 @@
+
+#include <algorithm>
+#include <cerrno>
+#include <cstring>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <Device/BlockDevice.h>
+#include <Cache/ConcreteBlockCache.h>
+
+#include <ProFUSE/Exception.h>
+#include <ProFUSE/auto.h>
+
+
+/*
+ * Note -- everything is assumed to be single-threaded.
+ *
+ */
+
+/*
+ * The primary purpose of the block cache is not as a cache 
+ * (the OS probably does a decent job of that) but rather to
+ * simplify read/writes. Blocks will always be accessed by
+ * pointer, so any updates will be shared.
+ * For memory mapped prodos-order files, MappedBlockCache just
+ * returns a pointer to the memory.
+ * For dos-order, nibblized, or raw devices, ConcreteBlockCache
+ * uses an approach similar to minix (although the buffer pool will 
+ * expand if needed).
+ *
+ * _buffers is a vector of all buffers and only exists to make
+ * freeing them easier.
+ * _hashTable is a simple hashtable of loaded blocks.
+ * _first and _last are a double-linked list of unused blocks, stored
+ * in lru order.
+ *
+ * The Entry struct contains the buffer, the block, a dirty flag, and an in-use
+ * count as well as pointer for the hashtable and lru list.
+ * When a block is loaded, it is stored in the _hashTable.  It remains in the 
+ * hash table when the in-use count goes to 0 (it will also be added to the
+ * end of the lru list).
+ * 
+ * dirty buffers are only written to disk in 3 scenarios:
+ * a) sync() is called
+ * b) the cache is deleted
+ * c) a buffer is re-used from the lru list.
+ */
+
+
+using namespace Device;
+
+using ProFUSE::Exception;
+using ProFUSE::POSIXException;
+
+
+//typedef std::vector<ConcreteBlockCache::Entry *>::iterator EntryIter;
+
+
+
+ConcreteBlockCache::ConcreteBlockCache(BlockDevice *device, unsigned size) :
+    BlockCache(device)
+{
+    if (size < 16) size = 16;
+    
+    std::memset(_hashTable, 0, sizeof(Entry *) * HashTableSize);
+    
+    for (unsigned i = 0; i < size; ++i)
+    {
+        Entry *e = new Entry;
+        
+        std::memset(e, 0, sizeof(Entry));
+        _buffers.push_back(e);
+    }
+    _first = _last = NULL;
+    
+    _first = _buffers.front();
+    _last = _buffers.back();
+    // form a chain....
+    for (unsigned i = 0; i < size; ++i)
+    {
+        Entry *e = _buffers[i];
+        
+        if (i > 0) e->prev = _buffers[i - 1];
+        
+        if (i < size - 1) e->next = _buffers[i + 1];
+    }
+    
+}
+
+ConcreteBlockCache::~ConcreteBlockCache()
+{
+    EntryIter iter;
+    for (iter = _buffers.begin(); iter != _buffers.end(); ++iter)
+    {
+        Entry *e = *iter;
+        
+        if (e->dirty)
+        {
+            _device->write(e->block, e->buffer);
+        }
+        
+        delete e;
+    }
+    _device->sync();
+}
+
+
+void ConcreteBlockCache::sync()
+{
+    EntryIter iter;
+    for (iter = _buffers.begin(); iter != _buffers.end(); ++iter)
+    {
+        Entry *e = *iter;
+        
+        if (e->dirty)
+        {
+            _device->write(e->block, e->buffer);
+            e->dirty = false;
+        }
+    }
+    _device->sync();
+}
+
+
+void ConcreteBlockCache::write(unsigned block, const void *bp)
+{
+    Entry *e = findEntry(block);
+    
+    if (e)
+    {
+        e->dirty = true;
+        std::memcpy(e->buffer, bp, 512);
+        return;
+    }
+    
+    // returns a new entry not in the hashtable or the linked list.
+    // we add it to both.
+    e = newEntry(block);
+    
+    e->count = 0;
+    e->dirty = true;
+    
+    std::memcpy(e->buffer, bp, 512);
+    
+    addEntry(e);
+    setLast(e);
+}
+
+
+
+void ConcreteBlockCache::markDirty(unsigned block)
+{
+    Entry *e = findEntry(block);
+    
+    if (e) e->dirty = true;
+    // error otherwise?
+}
+
+
+void ConcreteBlockCache::release(unsigned block, int flags)
+{
+    Entry *e = findEntry(block);
+    bool dirty = flags & (kBlockDirty | kBlockCommitNow);
+    
+    if (e)
+    {
+        if (dirty) e->dirty = true;    
+        
+        decrementCount(e);
+        
+        if (flags & kBlockCommitNow)
+        {
+            _device->write(block, e->buffer);
+            e->dirty = false;
+        }
+        
+    }
+    // error otherwise?
+}
+
+void *ConcreteBlockCache::acquire(unsigned block)
+{
+    Entry *e = findEntry(block);
+    
+    if (e)
+    {
+        incrementCount(e);
+        return e->buffer;
+    }
+    
+    // returns a new entry, not in hash table, not in free list.
+    e = newEntry(block);
+    
+    _device->read(block, e->buffer);
+    
+    addEntry(e);
+    
+    return e->buffer;
+}
+
+unsigned ConcreteBlockCache::hashFunction(unsigned block)
+{
+    return block % HashTableSize;
+}
+
+
+
+
+ConcreteBlockCache::Entry *ConcreteBlockCache::findEntry(unsigned block)
+{
+    Entry *e;
+    unsigned hash = hashFunction(block);
+    
+    e = _hashTable[hash];
+    
+    while ((e) && (e->block != block))
+        e = e->nextHash;
+
+    
+    return e;
+}
+
+
+/*
+ * remove a block from the hashtable
+ * and write to dick if dirty.
+ */
+void ConcreteBlockCache::removeEntry(unsigned block)
+{
+    Entry *e;
+    Entry *prev;
+    unsigned hash = hashFunction(block);
+    
+    e = _hashTable[hash];
+    if (!e) return;
+    
+    // head pointer, special case.
+    if (e->block == block)
+    {
+        _hashTable[hash] = e->nextHash;
+        e->nextHash = NULL;
+        
+        return;
+    }
+    
+    for(;;)
+    {
+        prev = e;
+        e = e->nextHash;
+        
+        if (!e) break;
+        if (e->block == block)
+        {
+            prev->nextHash = e->nextHash;
+            e->nextHash = NULL;
+            
+            break;
+        }    
+    }
+}
+
+
+void ConcreteBlockCache::addEntry(Entry *e)
+{
+    unsigned hash = hashFunction(e->block);
+    
+    e->nextHash = _hashTable[hash];
+    _hashTable[hash] = e;
+}
+
+// increment the count and remove from the free list
+// if necessary.
+void ConcreteBlockCache::incrementCount(Entry *e)
+{
+
+    if (e->count == 0)
+    {
+        Entry *prev = e->prev;
+        Entry *next = e->next;
+        
+        e->prev = e->next = NULL;
+
+        if (prev) prev->next = next;
+        if (next) next->prev = prev;
+        
+        if (_first == e) _first = next;
+        if (_last == e) _last = prev;
+    }
+    
+    e->count = e->count + 1;
+    
+}
+
+// decrement the count.  If it goes to 0,
+// add it as the last block entry.
+void ConcreteBlockCache::decrementCount(Entry *e)
+{
+    e->count = e->count - 1;
+    if (e->count == 0)
+    {
+        setLast(e);
+    }
+}
+
+ConcreteBlockCache::Entry *ConcreteBlockCache::newEntry(unsigned block)
+{
+    Entry *e;
+    
+    if (_first)
+    {
+        e = _first;
+        if (_first == _last)
+        {
+            _first = _last = NULL;
+        }
+        else
+        {
+            _first = e->next;
+            _first->prev = NULL; 
+        }
+
+
+        if (e->dirty)
+        {
+            _device->write(e->block, e->buffer);
+            e->dirty = false;
+        }
+        removeEntry(e->block);
+    }
+    else
+    {
+        e = new Entry;
+        _buffers.push_back(e);
+    }
+    
+    e->next = NULL;
+    e->prev= NULL;
+    e->nextHash = NULL;
+    e->count = 1;
+    e->block = block;
+    e->dirty = false;
+
+    return e;
+}
+
+
+void ConcreteBlockCache::setLast(Entry *e)
+{
+    if (_last == NULL)
+    {
+        _first = _last = e;
+        return;
+    }
+    
+    e->prev = _last;
+    _last->next = e;
+    _last = e;
+}
+
+
+void ConcreteBlockCache::setFirst(Entry *e)
+{
+    if (_first == NULL)
+    {
+        _first = _last = e;
+        return;
+    }
+    
+    e->next = _first;
+    _first->prev = e;
+    _first = e;
+}
+
diff --git a/Cache/ConcreteBlockCache.h b/Cache/ConcreteBlockCache.h
new file mode 100644
index 0000000..2ca5698
--- /dev/null
+++ b/Cache/ConcreteBlockCache.h
@@ -0,0 +1,70 @@
+#ifndef __CONCRETE_BLOCK_CACHE_H__
+#define __CONCRETE_BLOCK_CACHE_H__
+
+#include <vector>
+
+#include <Cache/BlockCache.h>
+
+namespace Device {
+
+class ConcreteBlockCache : public BlockCache {
+public:
+    ConcreteBlockCache(BlockDevice *device, unsigned size = 16);
+    virtual ~ConcreteBlockCache();
+
+    virtual void sync();
+    virtual void write(unsigned block, const void *vp);
+
+
+    virtual void *acquire(unsigned block);
+    virtual void release(unsigned block, int flags);
+    virtual void markDirty(unsigned block);
+
+    
+
+private:
+    struct Entry {
+        unsigned block;
+        unsigned count;
+        bool dirty;
+
+        struct Entry *next;
+        struct Entry *prev;
+        struct Entry *nextHash;
+
+        uint8_t buffer[512];
+
+    };
+
+    typedef std::vector<Entry *>::iterator EntryIter;
+    
+    enum { HashTableSize = 23 };
+
+    std::vector<Entry *>_buffers;
+
+    Entry *_hashTable[HashTableSize];
+
+    Entry *_first;
+    Entry *_last;
+
+
+    unsigned hashFunction(unsigned block);
+
+    Entry *findEntry(unsigned block);
+    void removeEntry(unsigned block);
+    void addEntry(Entry *);
+
+    Entry *newEntry(unsigned block);
+
+    void pushEntry(Entry *);
+
+    void setLast(Entry *);
+    void setFirst(Entry *);
+    
+    void incrementCount(Entry *);
+    void decrementCount(Entry *);
+};
+
+}
+
+#endif
diff --git a/Cache/MappedBlockCache.cpp b/Cache/MappedBlockCache.cpp
new file mode 100644
index 0000000..1d1be58
--- /dev/null
+++ b/Cache/MappedBlockCache.cpp
@@ -0,0 +1,134 @@
+
+#include <algorithm>
+#include <cerrno>
+#include <cstring>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <Cache/MappedBlockCache.h>
+#include <Device/BlockDevice.h>
+
+#include <ProFUSE/Exception.h>
+
+
+
+using namespace Device;
+
+using ProFUSE::Exception;
+using ProFUSE::POSIXException;
+
+
+MappedBlockCache::MappedBlockCache(BlockDevice *device, void *data) :
+    BlockCache(device)
+{
+    _data = (uint8_t *)data;
+    _dirty = false;
+}
+
+MappedBlockCache::~MappedBlockCache()
+{
+  if (_dirty) sync();
+}
+
+
+void *MappedBlockCache::acquire(unsigned block)
+{
+#undef __METHOD__
+#define __METHOD__ "MappedBlockCache::load"
+    
+    if (block >= blocks())
+        throw Exception(__METHOD__ ": Invalid block.");
+        
+    
+    return _data + block * 512;
+}
+
+void MappedBlockCache::release(unsigned block, int flags)
+{
+#undef __METHOD__
+#define __METHOD__ "MappedBlockCache::unload"
+
+    // kBlockCommitNow implies kBlockDirty. 
+    if (flags & kBlockCommitNow)
+    {
+        sync(block);
+        return;
+    }
+
+    if (flags & kBlockDirty) _dirty = true;
+}
+
+
+
+void MappedBlockCache::write(unsigned block, const void *vp)
+{
+#undef __METHOD__
+#define __METHOD__ "MappedBlockCache::write"
+    
+    if (block >= blocks())
+        throw Exception(__METHOD__ ": Invalid block.");
+    
+    _dirty = true;
+    std::memcpy(_data + block * 512, vp, 512);
+}
+
+
+void MappedBlockCache::zeroBlock(unsigned block)
+{
+#undef __METHOD__
+#define __METHOD__ "MappedBlockCache::zeroBlock"
+    
+    if (block >= blocks())
+        throw Exception(__METHOD__ ": Invalid block.");
+    
+    
+    _dirty = true;
+    std::memset(_data + block * 512, 0, 512);
+}
+
+
+
+// sync everything.
+void MappedBlockCache::sync()
+{
+  _device->sync();
+  _dirty = false;
+}
+
+/*
+ *
+ * sync an individual page.
+ *
+ */
+void MappedBlockCache::sync(unsigned block)
+{
+#undef __METHOD__
+#define __METHOD__ "MappedBlockCache::sync"
+
+
+    int pagesize = ::getpagesize();
+        
+    void *start = _data + block * 512;
+    void *end = _data + 512 + block * 512;
+
+
+    start = (void *)((ptrdiff_t)start / pagesize * pagesize);
+    end = (void *)((ptrdiff_t)end / pagesize * pagesize);
+
+    if (::msync(start, pagesize, MS_SYNC) != 0)
+        throw POSIXException(__METHOD__ ": msync", errno);
+    
+    if (start != end)
+    {
+        if (::msync(end, pagesize, MS_SYNC) != 0)
+            throw POSIXException(__METHOD__ ": msync", errno);    
+    }
+}
+
+void MappedBlockCache::markDirty(unsigned block)
+{
+    _dirty = true;
+}
+
diff --git a/Cache/MappedBlockCache.h b/Cache/MappedBlockCache.h
new file mode 100644
index 0000000..a3402ff
--- /dev/null
+++ b/Cache/MappedBlockCache.h
@@ -0,0 +1,35 @@
+#ifndef __MAPPED_BLOCK_CACHE_H__
+#define __MAPPED_BLOCK_CACHE_H__
+
+#include <Cache/BlockCache.h>
+
+namespace Device {
+
+class MappedBlockCache : public BlockCache {
+    public:
+
+    MappedBlockCache(BlockDevice *, void *data);
+    virtual ~MappedBlockCache();
+
+    virtual void sync();
+    virtual void write(unsigned block, const void *vp);
+
+    virtual void zeroBlock(unsigned block);    
+    
+
+    virtual void *acquire(unsigned block);
+    virtual void release(unsigned block, int flags);
+    virtual void markDirty(unsigned block);
+
+    private:
+    
+    void sync(unsigned block);
+        
+    uint8_t *_data;
+    bool _dirty;
+};
+
+} // namespace
+
+#endif
+