Multiple blocks per file

Change the block storage layer again, this time with multiple files
per block, but tracked by txindex.dat database entries. The file
format is exactly the same as the earlier blk00001.dat, but with
smaller files (128 MiB for now).

The database entries track how many bytes each block file already
uses, how many blocks are in it, which range of heights is present
and which range of dates.

1 files changed, 108 insertions, 18 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 8b1532e48c..15a2331376 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1399,6 +1399,8 @@ bool CBlock::DisconnectBlock(CTxDB& txdb, CBlockIndex* pindex)
     return true;
 }
 
+bool FindUndoPos(CTxDB &txdb, int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
+
 bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
 {
     // Check it again in case a previous version let a bad block in
@@ -1430,7 +1432,7 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
         // Since we're just checking the block and not actually connecting it, it might not (and probably shouldn't) be on the disk to get the transaction from
         nTxPos = 1;
     else
-        nTxPos = ::GetSerializeSize(CBlock(), SER_DISK, CLIENT_VERSION) - 1 + GetSizeOfCompactSize(vtx.size());
+        nTxPos = pindex->pos.nPos + ::GetSerializeSize(CBlock(), SER_DISK, CLIENT_VERSION) - 1 + GetSizeOfCompactSize(vtx.size());
 
     CBlockUndo blockundo;
 
@@ -1507,6 +1509,17 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
             return error("ConnectBlock() : UpdateTxIndex failed");
     }
 
+    // Write undo information to disk
+    if (pindex->GetUndoPos().IsNull() && pindex->nHeight > Checkpoints::GetTotalBlocksEstimate())
+    {
+        CDiskBlockPos pos;
+        if (!FindUndoPos(txdb, pindex->pos.nFile, pos, ::GetSerializeSize(blockundo, SER_DISK, CLIENT_VERSION) + 8))
+            return error("ConnectBlock() : FindUndoPos failed");
+        if (!blockundo.WriteToDisk(pos))
+            return error("ConnectBlock() : CBlockUndo::WriteToDisk failed");
+        pindex->nUndoPos = pos.nPos;
+    }
+
     // Update block index on disk without changing it in memory.
     // The memory index structure will be changed after the db commits.
     if (pindex->pprev)
@@ -1517,13 +1530,6 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
             return error("ConnectBlock() : WriteBlockIndex failed");
     }
 
-    // Write undo information to disk
-    if (pindex->nHeight > Checkpoints::GetTotalBlocksEstimate())
-    {
-        CAutoFile fileUndo(fopen(pindex->GetBlockPos().GetUndoFile(GetDataDir()).string().c_str(), "wb"), SER_DISK, CLIENT_VERSION);
-        fileUndo << blockundo;
-    }
-
     // Watch for transactions paying to me
     BOOST_FOREACH(CTransaction& tx, vtx)
         SyncWithWallets(tx, this, true);
@@ -1788,8 +1794,8 @@ bool CBlock::AddToBlockIndex(const CDiskBlockPos &pos)
         pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
     }
     pindexNew->bnChainWork = (pindexNew->pprev ? pindexNew->pprev->bnChainWork : 0) + pindexNew->GetBlockWork();
-    assert(pos.nHeight == pindexNew->nHeight);
-    pindexNew->nAlternative = pos.nAlternative;
+    pindexNew->pos = pos;
+    pindexNew->nUndoPos = 0;
 
     CTxDB txdb;
     if (!txdb.TxnBegin())
@@ -1819,6 +1825,57 @@ bool CBlock::AddToBlockIndex(const CDiskBlockPos &pos)
 
 
 
+bool FindBlockPos(CTxDB &txdb, CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64 nTime)
+{
+    bool fUpdatedLast = false;
+
+    LOCK(cs_LastBlockFile);
+
+    while (infoLastBlockFile.nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
+        printf("Leaving block file %i: %s\n", nLastBlockFile, infoLastBlockFile.ToString().c_str());
+        nLastBlockFile++;
+        infoLastBlockFile.SetNull();
+        txdb.ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile); // check whether data for the new file somehow already exist; can fail just fine
+        fUpdatedLast = true;
+    }
+
+    pos.nFile = nLastBlockFile;
+    pos.nPos = infoLastBlockFile.nSize;
+    infoLastBlockFile.nSize += nAddSize;
+    infoLastBlockFile.AddBlock(nHeight, nTime);
+
+    if (!txdb.WriteBlockFileInfo(nLastBlockFile, infoLastBlockFile))
+        return error("FindBlockPos() : cannot write updated block info");
+    if (fUpdatedLast)
+        txdb.WriteLastBlockFile(nLastBlockFile);
+
+    return true;
+}
+
+bool FindUndoPos(CTxDB &txdb, int nFile, CDiskBlockPos &pos, unsigned int nAddSize)
+{
+    pos.nFile = nFile;
+
+    LOCK(cs_LastBlockFile);
+
+    if (nFile == nLastBlockFile) {
+        pos.nPos = infoLastBlockFile.nUndoSize;
+        infoLastBlockFile.nUndoSize += nAddSize;
+        if (!txdb.WriteBlockFileInfo(nLastBlockFile, infoLastBlockFile))
+            return error("FindUndoPos() : cannot write updated block info");
+        return true;
+    }
+
+    CBlockFileInfo info;
+    if (!txdb.ReadBlockFileInfo(nFile, info))
+        return error("FindUndoPos() : cannot read block info");
+    pos.nPos = info.nUndoSize;
+    info.nUndoSize += nAddSize;
+    if (!txdb.WriteBlockFileInfo(nFile, info))
+        return error("FindUndoPos() : cannot write updated block info");
+    return true;
+}
+
 
 bool CBlock::CheckBlock(bool fCheckPOW, bool fCheckMerkleRoot) const
 {
@@ -1928,9 +1985,15 @@ bool CBlock::AcceptBlock()
     }
 
     // Write block to history file
-    CDiskBlockPos blockPos = CDiskBlockPos(nHeight);
+    unsigned int nBlockSize = ::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION);
     if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION)))
         return error("AcceptBlock() : out of disk space");
+    CDiskBlockPos blockPos;
+    {
+        CTxDB txdb;
+        if (!FindBlockPos(txdb, blockPos, nBlockSize+8, nHeight, nTime))
+            return error("AcceptBlock() : FindBlockPos failed");
+    }
     if (!WriteToDisk(blockPos))
         return error("AcceptBlock() : WriteToDisk failed");
     if (!AddToBlockIndex(blockPos))
@@ -2067,18 +2130,39 @@ bool CheckDiskSpace(uint64 nAdditionalBytes)
     return true;
 }
 
-FILE* OpenBlockFile(const CDiskBlockPos &pos, const char* pszMode)
+CCriticalSection cs_LastBlockFile;
+CBlockFileInfo infoLastBlockFile;
+int nLastBlockFile = 0;
+
+FILE* OpenDiskFile(const CDiskBlockPos &pos, const char *prefix, bool fReadOnly)
 {
-    boost::filesystem::path path = pos.GetFileName(GetDataDir());
-    boost::filesystem::create_directories(path.parent_path());
     if (pos.IsNull() || pos.IsMemPool())
         return NULL;
-    FILE* file = fopen(path.string().c_str(), pszMode);
+    boost::filesystem::path path = GetDataDir() / "blocks" / strprintf("%s%05u.dat", prefix, pos.nFile);
+    boost::filesystem::create_directories(path.parent_path());
+    FILE* file = fopen(path.string().c_str(), "rb+");
+    if (!file && !fReadOnly)
+        file = fopen(path.string().c_str(), "wb+");
     if (!file)
         return NULL;
+    if (pos.nPos) {
+        if (fseek(file, pos.nPos, SEEK_SET)) {
+            printf("Unable to seek to position %u of %s\n", pos.nPos, path.string().c_str());
+            fclose(file);
+            return NULL;
+        }
+    }
     return file;
 }
 
+FILE* OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly) {
+    return OpenDiskFile(pos, "blk", fReadOnly);
+}
+
+FILE *OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly) {
+    return OpenDiskFile(pos, "rev", fReadOnly);
+}
+
 bool LoadBlockIndex(bool fAllowNew)
 {
     if (fTestNet)
@@ -2146,7 +2230,13 @@ bool LoadBlockIndex(bool fAllowNew)
         assert(hash == hashGenesisBlock);
 
         // Start new block file
-        CDiskBlockPos blockPos(0);
+        unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
+        CDiskBlockPos blockPos;
+        {
+            CTxDB txdb;
+            if (!FindBlockPos(txdb, blockPos, nBlockSize+8, 0, block.nTime))
+                return error("AcceptBlock() : FindBlockPos failed");
+        }
         if (!block.WriteToDisk(blockPos))
             return error("LoadBlockIndex() : writing genesis block to disk failed");
         if (!block.AddToBlockIndex(blockPos))
@@ -2203,9 +2293,9 @@ void PrintBlockTree()
         // print item
         CBlock block;
         block.ReadFromDisk(pindex);
-        printf("%d (%s)  %s  tx %"PRIszu"",
+        printf("%d (blk%05u.dat:0x%lx)  %s  tx %"PRIszu"",
             pindex->nHeight,
-            pindex->GetBlockPos().GetFileName("").string().c_str(),
+            pindex->GetBlockPos().nFile, pindex->GetBlockPos().nPos,
             DateTimeStrFormat("%x %H:%M:%S", block.GetBlockTime()).c_str(),
             block.vtx.size());