env: add EnvMirror

This is an Env implementation that mirrors all storage-related methods on
two different backend Env's and verifies that they return the same
results (return status and read results).  This is useful for implementing
a new Env and verifying its correctness.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/include/rocksdb/env.h b/include/rocksdb/env.h
index 00fa52001e5cca0ea7962f6d2457c94d8da172bc..65fd67f03975231eb9e3f7c883aab4f736c4fb44 100644 (file)
--- a/include/rocksdb/env.h
+++ b/include/rocksdb/env.h
@@ -18,6 +18,7 @@
 #define STORAGE_ROCKSDB_INCLUDE_ENV_H_
 
 #include <stdint.h>
+#include <algorithm>
 #include <cstdarg>
 #include <limits>
 #include <memory>
@@ -615,6 +616,7 @@ class WritableFile {
 
  protected:
   friend class WritableFileWrapper;
+  friend class WritableFileMirror;
 
   Env::IOPriority io_priority_;
 };
@@ -943,6 +945,349 @@ class WritableFileWrapper : public WritableFile {
 // *base_env must remain live while the result is in use.
 Env* NewMemEnv(Env* base_env);
 
+// An implementaiton of Env that mirrors all work over two backend
+// Env's.  This is useful for debugging purposes.
+class SequentialFileMirror : public SequentialFile {
+ public:
+  unique_ptr<SequentialFile> a_, b_;
+  std::string fname;
+  SequentialFileMirror(std::string f) : fname(f) {}
+
+  Status Read(size_t n, Slice* result, char* scratch) {
+    Slice aslice;
+    Status as = a_->Read(n, &aslice, scratch);
+    if (as == Status::OK()) {
+      char bscratch[n];
+      Slice bslice;
+      unsigned off = 0;
+      size_t left = result->size();
+      while (left) {
+        Status bs = b_->Read(left, &bslice, bscratch);
+        assert(as == bs);
+        assert(memcmp(bscratch, scratch + off, bslice.size()) == 0);
+        off += bslice.size();
+        left -= bslice.size();
+      }
+      *result = aslice;
+    } else {
+      Status bs = b_->Read(n, result, scratch);
+      assert(as == bs);
+    }
+    return as;
+  }
+
+  Status Skip(uint64_t n) {
+    Status as = a_->Skip(n);
+    Status bs = b_->Skip(n);
+    assert(as == bs);
+    return as;
+  }
+  Status InvalidateCache(size_t offset, size_t length) {
+    Status as = a_->InvalidateCache(offset, length);
+    Status bs = b_->InvalidateCache(offset, length);
+    assert(as == bs);
+    return as;
+  };
+};
+
+class RandomAccessFileMirror : public RandomAccessFile {
+ public:
+  unique_ptr<RandomAccessFile> a_, b_;
+  std::string fname;
+  RandomAccessFileMirror(std::string f) : fname(f) {}
+
+  Status Read(uint64_t offset, size_t n, Slice* result, char* scratch) const {
+    Status as = a_->Read(offset, n, result, scratch);
+    if (as == Status::OK()) {
+      char bscratch[n];
+      Slice bslice;
+      unsigned off = 0;
+      size_t left = result->size();
+      while (left) {
+        Status bs = b_->Read(offset + off, left, &bslice, bscratch);
+        assert(as == bs);
+        assert(memcmp(bscratch, scratch + off, bslice.size()) == 0);
+        off += bslice.size();
+        left -= bslice.size();
+      }
+    } else {
+      Status bs = b_->Read(offset, n, result, scratch);
+      assert(as == bs);
+    }
+    return as;
+  }
+
+  bool ShouldForwardRawRequest() const {
+    // NOTE: not verified
+    return a_->ShouldForwardRawRequest();
+  }
+
+  size_t GetUniqueId(char* id, size_t max_size) const {
+    // NOTE: not verified
+    return a_->GetUniqueId(id, max_size);
+  }
+};
+
+class WritableFileMirror : public WritableFile {
+ public:
+  unique_ptr<WritableFile> a_, b_;
+  std::string fname;
+  WritableFileMirror(std::string f) : fname(f) {}
+
+  Status Append(const Slice& data) override {
+    Status as = a_->Append(data);
+    Status bs = b_->Append(data);
+    assert(as == bs);
+    return as;
+  }
+  Status PositionedAppend(const Slice& data, uint64_t offset) override {
+    Status as = a_->PositionedAppend(data, offset);
+    Status bs = b_->PositionedAppend(data, offset);
+    assert(as == bs);
+    return as;
+  }
+  Status Truncate(uint64_t size) override {
+    Status as = a_->Truncate(size);
+    Status bs = b_->Truncate(size);
+    assert(as == bs);
+    return as;
+  }
+  Status Close() override {
+    Status as = a_->Close();
+    Status bs = b_->Close();
+    assert(as == bs);
+    return as;
+  }
+  Status Flush() override {
+    Status as = a_->Flush();
+    Status bs = b_->Flush();
+    assert(as == bs);
+    return as;
+  }
+  Status Sync() override {
+    Status as = a_->Sync();
+    Status bs = b_->Sync();
+    assert(as == bs);
+    return as;
+  }
+  Status Fsync() override {
+    Status as = a_->Fsync();
+    Status bs = b_->Fsync();
+    assert(as == bs);
+    return as;
+  }
+  bool IsSyncThreadSafe() const override {
+    bool as = a_->IsSyncThreadSafe();
+    bool bs = b_->IsSyncThreadSafe();
+    assert(as == bs);
+    return as;
+  }
+  void SetIOPriority(Env::IOPriority pri) override {
+    a_->SetIOPriority(pri);
+    b_->SetIOPriority(pri);
+  }
+  Env::IOPriority GetIOPriority() override {
+    // NOTE: we don't verify this one
+    return a_->GetIOPriority();
+  }
+  uint64_t GetFileSize() override {
+    uint64_t as = a_->GetFileSize();
+    uint64_t bs = b_->GetFileSize();
+    assert(as == bs);
+    return as;
+  }
+  void GetPreallocationStatus(size_t* block_size,
+                              size_t* last_allocated_block) override {
+    // NOTE: we don't verify this one
+    return a_->GetPreallocationStatus(block_size, last_allocated_block);
+  }
+  size_t GetUniqueId(char* id, size_t max_size) const override {
+    // NOTE: we don't verify this one
+    return a_->GetUniqueId(id, max_size);
+  }
+  Status InvalidateCache(size_t offset, size_t length) override {
+    Status as = a_->InvalidateCache(offset, length);
+    Status bs = b_->InvalidateCache(offset, length);
+    assert(as == bs);
+    return as;
+  }
+
+ protected:
+  Status Allocate(uint64_t offset, uint64_t length) override {
+    Status as = a_->Allocate(offset, length);
+    Status bs = b_->Allocate(offset, length);
+    assert(as == bs);
+    return as;
+  }
+  Status RangeSync(uint64_t offset, uint64_t nbytes) override {
+    Status as = a_->RangeSync(offset, nbytes);
+    Status bs = b_->RangeSync(offset, nbytes);
+    assert(as == bs);
+    return as;
+  }
+};
+
+class EnvMirror : public EnvWrapper {
+  Env* a_, *b_;
+
+ public:
+  EnvMirror(Env* a, Env* b) : EnvWrapper(a), a_(a), b_(b) {}
+
+  Status NewSequentialFile(const std::string& f, unique_ptr<SequentialFile>* r,
+                           const EnvOptions& options) override {
+    if (f.find("/proc/") == 0) return a_->NewSequentialFile(f, r, options);
+    SequentialFileMirror* mf = new SequentialFileMirror(f);
+    r->reset(mf);
+    Status as = a_->NewSequentialFile(f, &mf->a_, options);
+    Status bs = b_->NewSequentialFile(f, &mf->b_, options);
+    assert(as == bs);
+    return as;
+  }
+  Status NewRandomAccessFile(const std::string& f,
+                             unique_ptr<RandomAccessFile>* r,
+                             const EnvOptions& options) override {
+    if (f.find("/proc/") == 0) return a_->NewRandomAccessFile(f, r, options);
+    RandomAccessFileMirror* mf = new RandomAccessFileMirror(f);
+    r->reset(mf);
+    Status as = a_->NewRandomAccessFile(f, &mf->a_, options);
+    Status bs = b_->NewRandomAccessFile(f, &mf->b_, options);
+    assert(as == bs);
+    return as;
+  }
+  Status NewWritableFile(const std::string& f, unique_ptr<WritableFile>* r,
+                         const EnvOptions& options) override {
+    if (f.find("/proc/") == 0) return a_->NewWritableFile(f, r, options);
+    WritableFileMirror* mf = new WritableFileMirror(f);
+    r->reset(mf);
+    Status as = a_->NewWritableFile(f, &mf->a_, options);
+    Status bs = b_->NewWritableFile(f, &mf->b_, options);
+    assert(as == bs);
+    return as;
+  }
+  Status ReuseWritableFile(const std::string& fname,
+                           const std::string& old_fname,
+                           unique_ptr<WritableFile>* r,
+                           const EnvOptions& options) override {
+    if (fname.find("/proc/") == 0)
+      return a_->ReuseWritableFile(fname, old_fname, r, options);
+    WritableFileMirror* mf = new WritableFileMirror(fname);
+    r->reset(mf);
+    Status as = a_->ReuseWritableFile(fname, old_fname, &mf->a_, options);
+    Status bs = b_->ReuseWritableFile(fname, old_fname, &mf->b_, options);
+    assert(as == bs);
+    return as;
+  }
+  virtual Status NewDirectory(const std::string& name,
+                              unique_ptr<Directory>* result) override {
+    unique_ptr<Directory> br;
+    Status as = a_->NewDirectory(name, result);
+    Status bs = b_->NewDirectory(name, &br);
+    assert(as == bs);
+    return as;
+  }
+  Status FileExists(const std::string& f) override {
+    Status as = a_->FileExists(f);
+    Status bs = b_->FileExists(f);
+    assert(as == bs);
+    return as;
+  }
+  Status GetChildren(const std::string& dir,
+                     std::vector<std::string>* r) override {
+    std::vector<std::string> ar, br;
+    Status as = a_->GetChildren(dir, &ar);
+    Status bs = b_->GetChildren(dir, &br);
+    assert(as == bs);
+    std::sort(ar.begin(), ar.end());
+    std::sort(br.begin(), br.end());
+    if (ar != br) {
+      assert(0 == "getchildren results don't match");
+    }
+    *r = ar;
+    return as;
+  }
+  Status DeleteFile(const std::string& f) override {
+    Status as = a_->DeleteFile(f);
+    Status bs = b_->DeleteFile(f);
+    assert(as == bs);
+    return as;
+  }
+  Status CreateDir(const std::string& d) override {
+    Status as = a_->CreateDir(d);
+    Status bs = b_->CreateDir(d);
+    assert(as == bs);
+    return as;
+  }
+  Status CreateDirIfMissing(const std::string& d) override {
+    Status as = a_->CreateDirIfMissing(d);
+    Status bs = b_->CreateDirIfMissing(d);
+    assert(as == bs);
+    return as;
+  }
+  Status DeleteDir(const std::string& d) override {
+    Status as = a_->DeleteDir(d);
+    Status bs = b_->DeleteDir(d);
+    assert(as == bs);
+    return as;
+  }
+  Status GetFileSize(const std::string& f, uint64_t* s) override {
+    uint64_t asize, bsize;
+    Status as = a_->GetFileSize(f, &asize);
+    Status bs = b_->GetFileSize(f, &bsize);
+    assert(as == bs);
+    assert(asize == bsize);
+    *s = asize;
+    return as;
+  }
+
+  Status GetFileModificationTime(const std::string& fname,
+                                 uint64_t* file_mtime) override {
+    uint64_t amtime, bmtime;
+    Status as = a_->GetFileModificationTime(fname, &amtime);
+    Status bs = b_->GetFileModificationTime(fname, &bmtime);
+    assert(as == bs);
+    assert(amtime - bmtime < 10000 || bmtime - amtime < 10000);
+    *file_mtime = amtime;
+    return as;
+  }
+
+  Status RenameFile(const std::string& s, const std::string& t) override {
+    Status as = a_->RenameFile(s, t);
+    Status bs = b_->RenameFile(s, t);
+    assert(as == bs);
+    return as;
+  }
+
+  Status LinkFile(const std::string& s, const std::string& t) override {
+    Status as = a_->LinkFile(s, t);
+    Status bs = b_->LinkFile(s, t);
+    assert(as == bs);
+    return as;
+  }
+
+  class FileLockMirror : public FileLock {
+   public:
+    FileLock* a_, *b_;
+    FileLockMirror(FileLock* a, FileLock* b) : a_(a), b_(b) {}
+  };
+
+  Status LockFile(const std::string& f, FileLock** l) override {
+    FileLock* al, *bl;
+    Status as = a_->LockFile(f, &al);
+    Status bs = b_->LockFile(f, &bl);
+    *l = new FileLockMirror(al, bl);
+    assert(as == bs);
+    return as;
+  }
+
+  Status UnlockFile(FileLock* l) override {
+    FileLockMirror* ml = static_cast<FileLockMirror*>(l);
+    Status as = a_->UnlockFile(ml->a_);
+    Status bs = b_->UnlockFile(ml->b_);
+    assert(as == bs);
+    return as;
+  }
+};
+
 }  // namespace rocksdb
 
 #endif  // STORAGE_ROCKSDB_INCLUDE_ENV_H_