tx fees, policy: read stale fee estimates with a regtest-only option

If -acceptstalefeeestimates option is passed stale fee estimates can now
be read when operating in regtest environments.

Additionally, this commit updates all declarations of the CBlockPolicyEstimator
class to include a the second constructor variable.

2 files changed, 6 insertions, 3 deletions

diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index a8ca8545d3..c8f2df781b 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -528,7 +528,7 @@ bool CBlockPolicyEstimator::_removeTx(const uint256& hash, bool inBlock)
     }
 }
 
-CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath)
+CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath, const bool read_stale_estimates)
     : m_estimation_filepath{estimation_filepath}
 {
     static_assert(MIN_BUCKET_FEERATE > 0, "Min feerate must be nonzero");
@@ -556,7 +556,7 @@ CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath
 
     std::chrono::hours file_age = GetFeeEstimatorFileAge();
     // fee estimate file must not be too old to avoid wrong fee estimates.
-    if (file_age > MAX_FILE_AGE) {
+    if (file_age > MAX_FILE_AGE && !read_stale_estimates) {
         LogPrintf("Fee estimation file %s too old (age=%lld > %lld hours) and will not be used to avoid serving stale estimates.\n", fs::PathToString(m_estimation_filepath), Ticks<std::chrono::hours>(file_age), Ticks<std::chrono::hours>(MAX_FILE_AGE));
         return;
     }
diff --git a/src/policy/fees.h b/src/policy/fees.h
index a348ba05d8..52761f03ca 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -30,6 +30,9 @@ static constexpr std::chrono::hours FEE_FLUSH_INTERVAL{1};
  */
 static constexpr std::chrono::hours MAX_FILE_AGE{60};
 
+// Whether we allow importing a fee_estimates file older than MAX_FILE_AGE.
+static constexpr bool DEFAULT_ACCEPT_STALE_FEE_ESTIMATES{false};
+
 class AutoFile;
 class CTxMemPoolEntry;
 class TxConfirmStats;
@@ -193,7 +196,7 @@ private:
     const fs::path m_estimation_filepath;
 public:
     /** Create new BlockPolicyEstimator and initialize stats tracking classes with default values */
-    CBlockPolicyEstimator(const fs::path& estimation_filepath);
+    CBlockPolicyEstimator(const fs::path& estimation_filepath, const bool read_stale_estimates);
     ~CBlockPolicyEstimator();
 
     /** Process all the transactions that have been included in a block */