Integrate "heap" metadata storage into blockstore

src/blockstore/v1/journal.h

@@ -0,0 +1,78 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
+#pragma once
+
+class blockstore_impl_t;
+
+struct journal_sector_info_t
+{
+    uint64_t offset;
+    uint64_t flush_count;
+    bool written;
+    bool dirty;
+    uint64_t submit_id;
+};
+
+struct pending_journaling_t
+{
+    int pending;
+    int sector;
+    blockstore_op_t *op;
+};
+
+struct journal_t
+{
+    int fd;
+    bool inmemory = false;
+    bool flush_journal = false;
+    void *buffer = NULL;
+
+    uint64_t block_size;
+    uint64_t offset, len;
+    // Next free block offset
+    uint64_t next_free = 0;
+    // First occupied block offset
+    uint64_t used_start = 0;
+    // End of the last block not used for writing anymore
+    uint64_t dirty_start = 0;
+    uint32_t crc32_last = 0;
+
+    // Current sector(s) used for writing
+    void *sector_buf = NULL;
+    journal_sector_info_t *sector_info = NULL;
+    uint64_t sector_count;
+    bool no_same_sector_overwrites = false;
+    int cur_sector = 0;
+    int in_sector_pos = 0;
+    std::vector<int> submitting_sectors;
+    std::multimap<uint64_t, pending_journaling_t> flushing_ops;
+    uint64_t submit_id = 0;
+
+    // Used sector map
+    // May use ~ 80 MB per 1 GB of used journal space in the worst case
+    std::map<uint64_t, uint64_t> used_sectors;
+
+    ~journal_t();
+    bool trim();
+    uint64_t get_trim_pos();
+    void dump_diagnostics();
+    inline bool entry_fits(int size)
+    {
+        return !(block_size - in_sector_pos < size ||
+            no_same_sector_overwrites && sector_info[cur_sector].written);
+    }
+};
+
+struct blockstore_journal_check_t
+{
+    blockstore_impl_t *bs;
+    uint64_t next_pos, next_sector, next_in_pos;
+    int sectors_to_write, first_sector;
+    bool right_dir; // writing to the end or the beginning of the ring buffer
+
+    blockstore_journal_check_t(blockstore_impl_t *bs);
+    int check_available(blockstore_op_t *op, int required, int size, int data_after);
+};
+
+journal_entry* prefill_single_journal_entry(journal_t & journal, uint16_t type, uint32_t size);