1 files changed, 145 insertions, 0 deletions
diff --git a/src/crimson/os/seastore/transaction.h b/src/crimson/os/seastore/transaction.h
new file mode 100644
index 000000000..e189d1d32
--- /dev/null
+++ b/src/crimson/os/seastore/transaction.h
@@ -0,0 +1,145 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#pragma once
+
+#include <iostream>
+
+#include "crimson/os/seastore/seastore_types.h"
+#include "crimson/os/seastore/cached_extent.h"
+#include "crimson/os/seastore/root_block.h"
+
+namespace crimson::os::seastore {
+
+/**
+ * Transaction
+ *
+ * Representation of in-progress mutation. Used exclusively through Cache methods.
+ */
+class Transaction {
+public:
+  using Ref = std::unique_ptr<Transaction>;
+  enum class get_extent_ret {
+    PRESENT,
+    ABSENT,
+    RETIRED
+  };
+  get_extent_ret get_extent(paddr_t addr, CachedExtentRef *out) {
+    if (retired_set.count(addr)) {
+      return get_extent_ret::RETIRED;
+    } else if (auto iter = write_set.find_offset(addr);
+	iter != write_set.end()) {
+      if (out)
+	*out = CachedExtentRef(&*iter);
+      return get_extent_ret::PRESENT;
+    } else if (
+      auto iter = read_set.find(addr);
+      iter != read_set.end()) {
+      if (out)
+	*out = CachedExtentRef(*iter);
+      return get_extent_ret::PRESENT;
+    } else {
+      return get_extent_ret::ABSENT;
+    }
+  }
+
+  void add_to_retired_set(CachedExtentRef ref) {
+    ceph_assert(!is_weak());
+    if (!ref->is_initial_pending()) {
+      // && retired_set.count(ref->get_paddr()) == 0
+      // If it's already in the set, insert here will be a noop,
+      // which is what we want.
+      retired_set.insert(ref);
+    } else {
+      ref->state = CachedExtent::extent_state_t::INVALID;
+    }
+    if (ref->is_pending()) {
+      write_set.erase(*ref);
+    }
+  }
+
+  void add_to_read_set(CachedExtentRef ref) {
+    if (is_weak()) return;
+
+    ceph_assert(read_set.count(ref) == 0);
+    read_set.insert(ref);
+  }
+
+  void add_fresh_extent(CachedExtentRef ref) {
+    ceph_assert(!is_weak());
+    fresh_block_list.push_back(ref);
+    ref->set_paddr(make_record_relative_paddr(offset));
+    offset += ref->get_length();
+    write_set.insert(*ref);
+  }
+
+  void add_mutated_extent(CachedExtentRef ref) {
+    ceph_assert(!is_weak());
+    mutated_block_list.push_back(ref);
+    write_set.insert(*ref);
+  }
+
+  void mark_segment_to_release(segment_id_t segment) {
+    assert(to_release == NULL_SEG_ID);
+    to_release = segment;
+  }
+
+  segment_id_t get_segment_to_release() const {
+    return to_release;
+  }
+
+  const auto &get_fresh_block_list() {
+    return fresh_block_list;
+  }
+
+  const auto &get_mutated_block_list() {
+    return mutated_block_list;
+  }
+
+  const auto &get_retired_set() {
+    return retired_set;
+  }
+
+  bool is_weak() const {
+    return weak;
+  }
+
+private:
+  friend class Cache;
+  friend Ref make_transaction();
+  friend Ref make_weak_transaction();
+
+  /**
+   * If set, *this may not be used to perform writes and will not provide
+   * consistentency allowing operations using to avoid maintaining a read_set.
+   */
+  const bool weak;
+
+  RootBlockRef root;        ///< ref to root if read or written by transaction
+
+  segment_off_t offset = 0; ///< relative offset of next block
+
+  pextent_set_t read_set;   ///< set of extents read by paddr
+  ExtentIndex write_set;    ///< set of extents written by paddr
+
+  std::list<CachedExtentRef> fresh_block_list;   ///< list of fresh blocks
+  std::list<CachedExtentRef> mutated_block_list; ///< list of mutated blocks
+
+  pextent_set_t retired_set; ///< list of extents mutated by this transaction
+
+  ///< if != NULL_SEG_ID, release this segment after completion
+  segment_id_t to_release = NULL_SEG_ID;
+
+  Transaction(bool weak) : weak(weak) {}
+};
+using TransactionRef = Transaction::Ref;
+
+inline TransactionRef make_transaction() {
+  return std::unique_ptr<Transaction>(new Transaction(false));
+}
+
+inline TransactionRef make_weak_transaction() {
+  return std::unique_ptr<Transaction>(new Transaction(true));
+}
+
+}