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[tracing] tracepoints to utxocache add, spent and uncache

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Signed-off-by: Arnab Sen <arnabsen1729@gmail.com>
pull/826/head
Arnab Sen 3 years ago
parent a26e8eef43
commit 2bc51c5c32
6 changed files with 208 additions and 10 deletions
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59
contrib/tracing/README.md
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@ -234,3 +234,62 @@ Histogram of block connection times in milliseconds (ms).
[16, 32) 9 | |
[32, 64) 4 | |
```
### log_utxocache_flush.py
A BCC Python script to log the cache and index flushes. Based on the
`utxocache:flush` tracepoint.
```bash
$ python3 contrib/tracing/log_utxocache_flush.py ./src/bitcoind
```
```
Logging utxocache flushes. Ctrl-C to end...
Duration (µs) Mode Coins Count Memory Usage Prune Full Flush
0 PERIODIC 28484 3929.87 kB False False
1 PERIODIC 28485 3930.00 kB False False
0 PERIODIC 28489 3930.51 kB False False
1 PERIODIC 28490 3930.64 kB False False
0 PERIODIC 28491 3930.77 kB False False
0 PERIODIC 28491 3930.77 kB False False
0 PERIODIC 28496 3931.41 kB False False
1 PERIODIC 28496 3931.41 kB False False
0 PERIODIC 28497 3931.54 kB False False
1 PERIODIC 28497 3931.54 kB False False
1 PERIODIC 28499 3931.79 kB False False
.
.
.
53788 ALWAYS 30076 4136.27 kB False False
7463 ALWAYS 0 245.84 kB False False
```
### log_utxos.bt
A `bpftrace` script to log information about the coins that are added, spent, or
uncached from the UTXO set. Based on the `utxocache:add`, `utxocache:spend` and
`utxocache:uncache` tracepoints.
```bash
$ bpftrace contrib/tracing/log_utxos.bt
```
It should produce an output similar to the following.
```bash
Attaching 4 probes...
OP Outpoint Value Height Coinbase
Added 6ba9ad857e1ef2eb2a2c94f06813c414c7ab273e3d6bd7ad64e000315a887e7c:1 10000 2094512 No
Spent fa7dc4db56637a151f6649d8f26732956d1c5424c82aae400a83d02b2cc2c87b:0 182264897 2094512 No
Added eeb2f099b1af6a2a12e6ddd2eeb16fc5968582241d7f08ba202d28b60ac264c7:0 10000 2094512 No
Added eeb2f099b1af6a2a12e6ddd2eeb16fc5968582241d7f08ba202d28b60ac264c7:1 182254756 2094512 No
Added a0c7f4ec9cccef2d89672a624a4e6c8237a17572efdd4679eea9e9ee70d2db04:0 10072679 2094513 Yes
Spent 25e0df5cc1aeb1b78e6056bf403e5e8b7e41f138060ca0a50a50134df0549a5e:2 540 2094508 No
Spent 42f383c04e09c26a2378272ec33aa0c1bf4883ca5ab739e8b7e06be5a5787d61:1 3848399 2007724 No
Added f85e3b4b89270863a389395cc9a4123e417ab19384cef96533c6649abd6b0561:0 3788399 2094513 No
Added f85e3b4b89270863a389395cc9a4123e417ab19384cef96533c6649abd6b0561:2 540 2094513 No
Spent a05880b8c77971ed0b9f73062c7c4cdb0ff3856ab14cbf8bc481ed571cd34b83:1 5591281046 2094511 No
Added eb689865f7d957938978d6207918748f74e6aa074f47874724327089445b0960:0 5589696005 2094513 No
Added eb689865f7d957938978d6207918748f74e6aa074f47874724327089445b0960:1 1565556 2094513 No
```

8
contrib/tracing/log_utxocache_flush.py
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@ -4,8 +4,8 @@ import sys
import ctypes
from bcc import BPF, USDT
""" Example script to log details about coins flushed by the Bitcoin client
utilizing USDT probes and the flush:flush tracepoint. """
"""Example logging Bitcoin Core utxo set cache flushes utilizing
the utxocache:flush tracepoint."""
# USAGE: ./contrib/tracing/log_utxocache_flush.py path/to/bitcoind
@ -22,8 +22,10 @@ struct data_t
bool is_flush_prune;
bool is_full_flush;
};
// BPF perf buffer to push the data to user space.
BPF_PERF_OUTPUT(flush);
int trace_flush(struct pt_regs *ctx) {
struct data_t data = {};
bpf_usdt_readarg(1, ctx, &data.duration);
@ -45,8 +47,8 @@ FLUSH_MODES = [
]
# define output data structure
class Data(ctypes.Structure):
# define output data structure corresponding to struct data_t
_fields_ = [
("duration", ctypes.c_uint64),
("mode", ctypes.c_uint32),

86
contrib/tracing/log_utxos.bt
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@ -0,0 +1,86 @@
#!/usr/bin/env bpftrace
/*
USAGE:
bpftrace contrib/tracing/log_utxos.bt
This script requires a 'bitcoind' binary compiled with eBPF support and the
'utxochache' tracepoints. By default, it's assumed that 'bitcoind' is
located in './src/bitcoind'. This can be modified in the script below.
NOTE: requires bpftrace v0.12.0 or above.
*/
BEGIN
{
printf("%-7s %-71s %16s %7s %8s\n",
"OP", "Outpoint", "Value", "Height", "Coinbase");
}
/*
Attaches to the 'utxocache:add' tracepoint and prints additions to the UTXO set cache.
*/
usdt:./src/bitcoind:utxocache:add
{
$txid = arg0;
$index = (uint32)arg1;
$height = (uint32)arg2;
$value = (int64)arg3;
$isCoinbase = arg4;
printf("Added ");
$p = $txid + 31;
unroll(32) {
$b = *(uint8*)$p;
printf("%02x", $b);
$p-=1;
}
printf(":%-6d %16ld %7d %s\n", $index, $value, $height, ($isCoinbase ? "Yes" : "No" ));
}
/*
Attaches to the 'utxocache:spent' tracepoint and prints spents from the UTXO set cache.
*/
usdt:./src/bitcoind:utxocache:spent
{
$txid = arg0;
$index = (uint32)arg1;
$height = (uint32)arg2;
$value = (int64)arg3;
$isCoinbase = arg4;
printf("Spent ");
$p = $txid + 31;
unroll(32) {
$b = *(uint8*)$p;
printf("%02x", $b);
$p-=1;
}
printf(":%-6d %16ld %7d %s\n", $index, $value, $height, ($isCoinbase ? "Yes" : "No" ));
}
/*
Attaches to the 'utxocache:uncache' tracepoint and uncache UTXOs from the UTXO set cache.
*/
usdt:./src/bitcoind:utxocache:uncache
{
$txid = arg0;
$index = (uint32)arg1;
$height = (uint32)arg2;
$value = (int64)arg3;
$isCoinbase = arg4;
printf("Uncache ");
$p = $txid + 31;
unroll(32) {
$b = *(uint8*)$p;
printf("%02x", $b);
$p-=1;
}
printf(":%-6d %16ld %7d %s\n", $index, $value, $height, ($isCoinbase ? "Yes" : "No" ));
}

33
doc/tracing.md
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@ -124,6 +124,39 @@ Arguments passed:
5. If the flush was pruned as `bool`
6. If it was full flush as `bool`
#### Tracepoint `utxocache:add`
It is called when a new coin is added to the UTXO cache.
Arguments passed:
1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian)
2. Output index as `uint32`
3. Block height the coin was added to the UTXO-set as `uint32`
4. Value of the coin as `int64`
5. If the coin is a coinbase as `bool`
#### Tracepoint `utxocache:spent`
It is called when a coin is spent from the UTXO cache.
Arguments passed:
1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian)
2. Output index as `uint32`
3. Block height the coin was spent, as `uint32`
4. Value of the coin as `int64`
5. If the coin is a coinbase as `bool`
#### Tracepoint `utxocache:uncache`
It is called when the UTXO with the given outpoint is removed from the cache.
Arguments passed:
1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian)
2. Output index as `uint32`
3. Block height the coin was uncached, as `uint32`
4. Value of the coin as `int64`
. If the coin is a coinbase as `bool`
## Adding tracepoints to Bitcoin Core
To add a new tracepoint, `#include <util/trace.h>` in the compilation unit where

19
src/coins.cpp
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@ -7,6 +7,7 @@
#include <consensus/consensus.h>
#include <logging.h>
#include <random.h>
#include <util/trace.h>
#include <version.h>
bool CCoinsView::GetCoin(const COutPoint &outpoint, Coin &coin) const { return false; }
@ -95,6 +96,12 @@ void CCoinsViewCache::AddCoin(const COutPoint &outpoint, Coin&& coin, bool possi
it->second.coin = std::move(coin);
it->second.flags |= CCoinsCacheEntry::DIRTY | (fresh ? CCoinsCacheEntry::FRESH : 0);
cachedCoinsUsage += it->second.coin.DynamicMemoryUsage();
TRACE5(utxocache, add,
outpoint.hash.data(),
(uint32_t)outpoint.n,
(uint32_t)coin.nHeight,
(int64_t)coin.out.nValue,
(bool)coin.IsCoinBase());
}
void CCoinsViewCache::EmplaceCoinInternalDANGER(COutPoint&& outpoint, Coin&& coin) {
@ -120,6 +127,12 @@ bool CCoinsViewCache::SpendCoin(const COutPoint &outpoint, Coin* moveout) {
CCoinsMap::iterator it = FetchCoin(outpoint);
if (it == cacheCoins.end()) return false;
cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
TRACE5(utxocache, spent,
outpoint.hash.data(),
(uint32_t)outpoint.n,
(uint32_t)it->second.coin.nHeight,
(int64_t)it->second.coin.out.nValue,
(bool)it->second.coin.IsCoinBase());
if (moveout) {
*moveout = std::move(it->second.coin);
}
@ -231,6 +244,12 @@ void CCoinsViewCache::Uncache(const COutPoint& hash)
CCoinsMap::iterator it = cacheCoins.find(hash);
if (it != cacheCoins.end() && it->second.flags == 0) {
cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
TRACE5(utxocache, uncache,
hash.hash.data(),
(uint32_t)hash.n,
(uint32_t)it->second.coin.nHeight,
(int64_t)it->second.coin.out.nValue,
(bool)it->second.coin.IsCoinBase());
cacheCoins.erase(it);
}
}

13
src/validation.cpp
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@ -2102,13 +2102,12 @@ bool CChainState::FlushStateToDisk(
full_flush_completed = true;
}
TRACE6(utxocache, flush,
(int64_t)(GetTimeMicros() - nNow.count()), // in microseconds (µs)
(u_int32_t)mode,
(u_int64_t)coins_count,
(u_int64_t)coins_mem_usage,
(bool)fFlushForPrune,
(bool)fDoFullFlush
);
(int64_t)(GetTimeMicros() - nNow.count()), // in microseconds (µs)
(u_int32_t)mode,
(u_int64_t)coins_count,
(u_int64_t)coins_mem_usage,
(bool)fFlushForPrune,
(bool)fDoFullFlush);
}
if (full_flush_completed) {
// Update best block in wallet (so we can detect restored wallets).

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