1 files changed, 156 insertions, 0 deletions
diff --git a/core/mempool.hpp b/core/mempool.hpp
new file mode 100644
index 0000000..a5ac07b
--- /dev/null
+++ b/core/mempool.hpp
@@ -0,0 +1,156 @@
+#ifndef qEzyOXbTTD6KlhKDUsawdWmx6c0
+#define qEzyOXbTTD6KlhKDUsawdWmx6c0
+
+#include <assert.h>
+#include <fcntl.h>
+#include <malloc.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <string>
+
+#include <boost/utility.hpp>
+
+using std::string;
+
+struct MemPool : boost::noncopyable {
+  explicit MemPool(size_t size); // anonymous in-memory-pool
+  MemPool(size_t size, int fd); // mmap()ed memory pool
+  MemPool(size_t size, const string filename); // mmap()ed memory pool
+  MemPool(MemPool &&src); // move ctor
+  MemPool& operator=(MemPool&&);
+  MemPool& operator=(MemPool&) = delete;
+  MemPool& operator=(MemPool) = delete;
+
+  ~MemPool();
+
+  inline void* operator() () const; // return memory region; TODO: pure attr
+  inline size_t getSize() const;
+  void sync() const; // call msync()
+  void advise(size_t start, size_t len, int adv);
+
+protected:
+  void *base;
+  size_t size;
+  bool isMMap;
+
+  void doMMap(int fd, size_t size);
+  int openMMappableFile(const string filename, size_t size);
+
+private:
+  static char* global_offset;
+  MemPool() = delete;
+  MemPool(const MemPool&) = delete;
+};
+
+char* MemPool::global_offset = (char*) (void*) 0x2fffff000000;
+
+inline void* MemPool::operator() () const {
+  return base;
+}
+
+inline size_t MemPool::getSize() const {
+  return size;
+}
+
+MemPool::MemPool(size_t size) : size(size), isMMap(false) {
+  if (size == 0) {
+    base = NULL;
+  }else{
+    base = malloc(size);
+    assert(base != NULL);
+  }
+}
+
+MemPool::MemPool(size_t size, int fd) : size(size),isMMap(true) {
+  if (size == 0) {
+    base = NULL;
+  }else{
+    doMMap(fd, size);
+  }
+}
+
+MemPool::MemPool(size_t size, const string filename) : size(size), isMMap(true) {
+  if (size == 0) {
+    base = NULL;
+  }else{
+    doMMap(openMMappableFile(filename, size), size);
+  }
+}
+
+MemPool::MemPool(MemPool &&src) : base(src.base), size(src.size), isMMap(src.isMMap) {
+  //  std::cout << "Mempool " << base << " moved via copy" << std::endl;
+  src.base = NULL;
+  src.size = 0;
+}
+
+MemPool& MemPool::operator= (MemPool &&src) {
+  //  std::cout << "Mempool " << base << " moved via assignment" << std::endl;
+  base = src.base;
+  size = src.size;
+  isMMap = src.isMMap;
+  src.base = NULL;
+  src.size = 0;
+  return *this;
+}
+
+MemPool::~MemPool() {
+  //  std::cout << "Mempool " << base << " terminated";
+  if (size == 0 or base == NULL) {
+    //  std::cout << " from move" << std::endl;
+    return;
+  }else{
+    //    std::cout << std::endl;
+  }
+  if (isMMap) {
+    sync();
+    munmap(base, size);
+  }else{
+    free(base);
+  }
+}
+
+void MemPool::sync() const {
+  if (isMMap)
+    msync(base, size, MS_SYNC);
+}
+
+void MemPool::advise(size_t start, size_t len, int adv)  {
+  // adjust region to page boundary (defensive)
+  if (start & 4095) {
+    len -= 4096 - (start & 4095);
+    len &= ~4095;
+    start &= 4095;
+    start +=1;
+  }
+  // detect underflow and to large len
+  if (len < size) {
+    assert(madvise((char*) base + start, len, adv) == 0);
+  }
+}
+
+void MemPool::doMMap(int fd, size_t size) {
+  base = (void*) mmap((void*) global_offset, size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_NONBLOCK, fd, 0);
+  assert(base != MAP_FAILED);
+  assert(base == (void*) global_offset);
+  global_offset += ((size / 4096 + 1) * 4096) + 1024 * 4096;
+}
+
+int MemPool::openMMappableFile(const string filename, size_t size) {
+  int fd = open(filename.c_str(), O_RDWR | O_CREAT | O_LARGEFILE | O_NOATIME, 0644);
+  assert(fd != -1);
+
+  // check if the file size is correct
+  struct stat st;
+  fstat(fd, &st);
+  if ((size_t) st.st_size < size) {
+    // write one byte at the end of the file to make it big enough for the later mmap call (mmap does not increase file size)
+    assert(lseek64(fd, size-1, SEEK_SET) != (off_t) -1);
+    char c(0);
+    assert(write(fd, &c, 1) == 1);
+  }
+
+  return fd;
+}
+
+#endif // qEzyOXbTTD6KlhKDUsawdWmx6c0