比特币 RPC 命令「gettxoutsetinfo」
$ bitcoin-cli help gettxoutsetinfo
gettxoutsetinfo
返回关于未花费交易输出集合的统计信息。
注意该调用可能会花费一些时间。
结果：
{
"height":n, （数字）当前的区块高度（索引）
"bestblock": "hex", （字符串）最佳区块哈希 16 进制
"transactions": n, （数字）交易数
"txouts": n, （数字）交易输出数
"bytes_serialized": n, （数字）序列化的大小
"hash_serialized": "hash",（字符串）序列化的哈希
"total_amount": x.xxx （数字）总金额
}
例子：
> bitcoin-cli gettxoutsetinfo
> curl --user myusername:mypassword --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "gettxoutsetinfo", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:8332/
源码剖析
gettxoutsetinfo 对应的函数在文件 rpcserver.h 中被引用。
extern UniValue gettxoutsetinfo(const UniValue& params, bool fHelp);
实现在文件 rpcblockchain.cpp 中。
UniValue gettxoutsetinfo(const UniValue& params, bool fHelp)
{
if (fHelp || params.size() != 0)
throw runtime_error(
"gettxoutsetinfo\n"
"\nReturns statistics about the unspent transaction output set.\n"
"Note this call may take some time.\n"
"\nResult:\n"
"{\n"
" \"height\":n, (numeric) The current block height (index)\n"
" \"bestblock\": \"hex\", (string) the best block hash hex\n"
" \"transactions\": n, (numeric) The number of transactions\n"
" \"txouts\": n, (numeric) The number of output transactions\n"
" \"bytes_serialized\": n, (numeric) The serialized size\n"
" \"hash_serialized\": \"hash\", (string) The serialized hash\n"
" \"total_amount\": x.xxx (numeric) The total amount\n"
"}\n"
"\nExamples:\n"
+ HelpExampleCli("gettxoutsetinfo", "")
+ HelpExampleRpc("gettxoutsetinfo", "")
); // 1. 帮助内容
UniValue ret(UniValue::VOBJ);
CCoinsStats stats;
FlushStateToDisk(); // 2. 刷新状态到磁盘
if (pcoinsTip->GetStats(stats)) { // 获取币状态信息
ret.push_back(Pair("height", (int64_t)stats.nHeight)); // 区块链高度
ret.push_back(Pair("bestblock", stats.hashBlock.GetHex())); // 最佳区块哈希
ret.push_back(Pair("transactions", (int64_t)stats.nTransactions)); // 交易数
ret.push_back(Pair("txouts", (int64_t)stats.nTransactionOutputs)); // 交易输出数
ret.push_back(Pair("bytes_serialized", (int64_t)stats.nSerializedSize)); // 序列化的大小
ret.push_back(Pair("hash_serialized", stats.hashSerialized.GetHex())); // 序列化的哈希
ret.push_back(Pair("total_amount", ValueFromAmount(stats.nTotalAmount))); // 总金额
}
return ret;
}
1. 帮助内容
参考比特币 RPC 命令「getbestblockhash」1. 帮助内容。
2. 刷新状态到磁盘
刷新状态到磁盘函数 FlushStateToDisk() 声明在文件 main.h 中。
/** Flush all state, indexes and buffers to disk. */
void FlushStateToDisk(); // 刷新所有状态、索引集和缓存到磁盘。
实现在文件 main.cpp 中。
/**
* Update the on-disk chain state.
* The caches and indexes are flushed depending on the mode we're called with
* if they're too large, if it's been a while since the last write,
* or always and in all cases if we're in prune mode and are deleting files.
*/
bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
const CChainParams& chainparams = Params();
LOCK2(cs_main, cs_LastBlockFile);
static int64_t nLastWrite = 0;
static int64_t nLastFlush = 0;
static int64_t nLastSetChain = 0;
std::set<int> setFilesToPrune;
bool fFlushForPrune = false;
try {
if (fPruneMode && fCheckForPruning && !fReindex) {
FindFilesToPrune(setFilesToPrune, chainparams.PruneAfterHeight());
fCheckForPruning = false;
if (!setFilesToPrune.empty()) {
fFlushForPrune = true;
if (!fHavePruned) {
pblocktree->WriteFlag("prunedblockfiles", true);
fHavePruned = true;
}
}
}
int64_t nNow = GetTimeMicros();
// Avoid writing/flushing immediately after startup.
if (nLastWrite == 0) {
nLastWrite = nNow;
}
if (nLastFlush == 0) {
nLastFlush = nNow;
}
if (nLastSetChain == 0) {
nLastSetChain = nNow;
}
size_t cacheSize = pcoinsTip->DynamicMemoryUsage();
// The cache is large and close to the limit, but we have time now (not in the middle of a block processing).
bool fCacheLarge = mode == FLUSH_STATE_PERIODIC && cacheSize * (10.0/9) > nCoinCacheUsage;
// The cache is over the limit, we have to write now.
bool fCacheCritical = mode == FLUSH_STATE_IF_NEEDED && cacheSize > nCoinCacheUsage;
// It's been a while since we wrote the block index to disk. Do this frequently, so we don't need to redownload after a crash.
bool fPeriodicWrite = mode == FLUSH_STATE_PERIODIC && nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
// It's been very long since we flushed the cache. Do this infrequently, to optimize cache usage.
bool fPeriodicFlush = mode == FLUSH_STATE_PERIODIC && nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
// Combine all conditions that result in a full cache flush.
bool fDoFullFlush = (mode == FLUSH_STATE_ALWAYS) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
// Write blocks and block index to disk.
if (fDoFullFlush || fPeriodicWrite) {
// Depend on nMinDiskSpace to ensure we can write block index
if (!CheckDiskSpace(0))
return state.Error("out of disk space");
// First make sure all block and undo data is flushed to disk.
FlushBlockFile();
// Then update all block file information (which may refer to block and undo files).
{
std::vector<std::pair<int, const CBlockFileInfo*> > vFiles;
vFiles.reserve(setDirtyFileInfo.size());
for (set<int>::iterator it = setDirtyFileInfo.begin(); it != setDirtyFileInfo.end(); ) {
vFiles.push_back(make_pair(*it, &vinfoBlockFile[*it]));
setDirtyFileInfo.erase(it++);
}
std::vector<const CBlockIndex*> vBlocks;
vBlocks.reserve(setDirtyBlockIndex.size());
for (set<CBlockIndex*>::iterator it = setDirtyBlockIndex.begin(); it != setDirtyBlockIndex.end(); ) {
vBlocks.push_back(*it);
setDirtyBlockIndex.erase(it++);
}
if (!pblocktree->WriteBatchSync(vFiles, nLastBlockFile, vBlocks)) {
return AbortNode(state, "Files to write to block index database");
}
}
// Finally remove any pruned files
if (fFlushForPrune)
UnlinkPrunedFiles(setFilesToPrune);
nLastWrite = nNow;
}
// Flush best chain related state. This can only be done if the blocks / block index write was also done.
if (fDoFullFlush) {
// Typical CCoins structures on disk are around 128 bytes in size.
// Pushing a new one to the database can cause it to be written
// twice (once in the log, and once in the tables). This is already
// an overestimation, as most will delete an existing entry or
// overwrite one. Still, use a conservative safety factor of 2.
if (!CheckDiskSpace(128 * 2 * 2 * pcoinsTip->GetCacheSize()))
return state.Error("out of disk space");
// Flush the chainstate (which may refer to block index entries).
if (!pcoinsTip->Flush())
return AbortNode(state, "Failed to write to coin database");
nLastFlush = nNow;
}
if (fDoFullFlush || ((mode == FLUSH_STATE_ALWAYS || mode == FLUSH_STATE_PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000)) {
// Update best block in wallet (so we can detect restored wallets).
GetMainSignals().SetBestChain(chainActive.GetLocator());
nLastSetChain = nNow;
}
} catch (const std::runtime_error& e) {
return AbortNode(state, std::string("System error while flushing: ") + e.what());
}
return true;
}
void FlushStateToDisk() {
CValidationState state;
FlushStateToDisk(state, FLUSH_STATE_ALWAYS);
}
更新磁盘上的链状态。 如果缓存和索引过大，或距上一次写操作已经过了一段时间，或我们处于修剪模式并正在删除文件，则根据调用的模式刷新缓存和索引。