Show the number of transactions in pool job

Useful to check if pool/proxy is working properly and can also be used to compare different pools.

src/base/net/stratum/Job.cpp

@@ -163,6 +163,31 @@ void xmrig::Job::setSigKey(const char *sig_key)
 }
 
 
+uint32_t xmrig::Job::getNumTransactions() const
+{
+    if (m_algorithm.family() > Algorithm::RANDOM_X) {
+        return 0;
+    }
+
+    uint32_t num_transactions = 0;
+
+    // Monero (and some other coins) has the number of transactions encoded as varint in the end of hashing blob
+    const size_t expected_tx_offset = (m_algorithm == Algorithm::RX_WOW) ? 141 : 75;
+
+    if ((m_size > expected_tx_offset) && (m_size <= expected_tx_offset + 4)) {
+        for (size_t i = expected_tx_offset, k = 0; i < m_size; ++i, k += 7) {
+            const uint8_t b = m_blob[i];
+            num_transactions |= static_cast<uint32_t>(b & 0x7F) << k;
+            if ((b & 0x80) == 0) {
+                break;
+            }
+        }
+    }
+
+    return num_transactions;
+}
+
+
 void xmrig::Job::copy(const Job &other)
 {
     m_algorithm  = other.m_algorithm;