Parametrize timespan constants.

The constants are parametrized such that libbitcoin can
be used by various altcoins by solely editing the
config file.

Makefile.am

@@ -37,6 +37,7 @@ src_libbitcoin_la_LDFLAGS = ${boost_LDFLAGS}
 src_libbitcoin_la_LIBADD = ${boost_chrono_LIBS} ${boost_date_time_LIBS} ${boost_filesystem_LIBS} ${boost_iostreams_LIBS} ${boost_locale_LIBS} ${boost_log_LIBS} ${boost_program_options_LIBS} ${boost_regex_LIBS} ${boost_system_LIBS} ${boost_thread_LIBS} ${pthread_LIBS} ${rt_LIBS} ${icu_i18n_LIBS} ${dl_LIBS} ${png_LIBS} ${qrencode_LIBS} ${secp256k1_LIBS}
 src_libbitcoin_la_SOURCES = \
     src/error.cpp \
+    src/settings.cpp \
     src/chain/block.cpp \
     src/chain/chain_state.cpp \
     src/chain/compact.cpp \
@@ -363,6 +364,7 @@ include_bitcoin_bitcoin_HEADERS = \
     include/bitcoin/bitcoin/define.hpp \
     include/bitcoin/bitcoin/error.hpp \
     include/bitcoin/bitcoin/handlers.hpp \
+    include/bitcoin/bitcoin/settings.hpp \
     include/bitcoin/bitcoin/version.hpp
 
 include_bitcoin_bitcoin_chaindir = ${includedir}/bitcoin/bitcoin/chain

include/bitcoin/bitcoin/chain/chain_state.hpp

@@ -23,6 +23,7 @@
 #include <cstdint>
 #include <memory>
 #include <deque>
+#include <bitcoin/bitcoin/settings.hpp>
 #include <bitcoin/bitcoin/config/checkpoint.hpp>
 #include <bitcoin/bitcoin/constants.hpp>
 #include <bitcoin/bitcoin/define.hpp>
@@ -124,24 +125,26 @@ class BC_API chain_state
     };
 
     /// Checkpoints must be ordered by height with greatest at back.
-    static map get_map(size_t height, const checkpoints& checkpoints,
+    map get_map(size_t height, const checkpoints& checkpoints,
         uint32_t forks);
 
     static uint32_t signal_version(uint32_t forks);
 
     /// Create pool state from top chain top block state.
-    chain_state(const chain_state& top);
+    chain_state(const chain_state& top, const settings& settings);
 
     /// Create block state from tx pool chain state of same height.
-    chain_state(const chain_state& pool, const chain::block& block);
+    chain_state(const chain_state& pool, const chain::block& block,
+        const settings& settings);
 
     /// Create header state from header pool chain state of parent block.
-    chain_state(const chain_state& parent, const chain::header& header);
+    chain_state(const chain_state& parent, const chain::header& header,
+        const settings& settings);
 
     /// Checkpoints must be ordered by height with greatest at back.
     /// Forks and checkpoints must match those provided for map creation.
     chain_state(data&& values, const checkpoints& checkpoints, uint32_t forks,
-        uint32_t stale_seconds);
+        uint32_t stale_seconds, const settings& settings);
 
     /// Properties.
     size_t height() const;
@@ -181,29 +184,29 @@ class BC_API chain_state
 
     static activations activation(const data& values, uint32_t forks);
     static uint32_t median_time_past(const data& values, uint32_t forks);
-    static uint32_t work_required(const data& values, uint32_t forks);
+    uint32_t work_required(const data& values, uint32_t forks);
 
 private:
-    static size_t bits_count(size_t height, uint32_t forks);
+    size_t bits_count(size_t height, uint32_t forks);
     static size_t version_count(size_t height, uint32_t forks);
     static size_t timestamp_count(size_t height, uint32_t forks);
-    static size_t retarget_height(size_t height, uint32_t forks);
+    size_t retarget_height(size_t height, uint32_t forks);
     static size_t bip9_bit0_height(size_t height, uint32_t forks);
     static size_t bip9_bit1_height(size_t height, uint32_t forks);
 
-    static data to_pool(const chain_state& top);
+    data to_pool(const chain_state& top);
     static data to_block(const chain_state& pool, const block& block);
-    static data to_header(const chain_state& parent, const header& header);
+    data to_header(const chain_state& parent, const header& header);
 
-    static uint32_t work_required_retarget(const data& values);
-    static uint32_t retarget_timespan(const chain_state::data& values);
+    uint32_t work_required_retarget(const data& values);
+    uint32_t retarget_timespan(const chain_state::data& values);
 
     // easy blocks
-    static uint32_t easy_work_required(const data& values);
-    static uint32_t easy_time_limit(const chain_state::data& values);
-    static bool is_retarget_or_non_limit(size_t height, uint32_t bits);
-    static bool is_retarget_height(size_t height);
-    static size_t retarget_distance(size_t height);
+    uint32_t easy_work_required(const data& values);
+    uint32_t easy_time_limit(const chain_state::data& values);
+    bool is_retarget_or_non_limit(size_t height, uint32_t bits);
+    bool is_retarget_height(size_t height);
+    size_t retarget_distance(size_t height);
 
     // This is retained as an optimization for other constructions.
     // A similar height clone can be partially computed, reducing query cost.
@@ -222,6 +225,7 @@ class BC_API chain_state
     const activations active_;
     const uint32_t median_time_past_;
     const uint32_t work_required_;
+    const settings& settings_;
 };
 
 } // namespace chain

include/bitcoin/bitcoin/chain/header.hpp

@@ -28,6 +28,7 @@
 #include <bitcoin/bitcoin/chain/chain_state.hpp>
 #include <bitcoin/bitcoin/define.hpp>
 #include <bitcoin/bitcoin/error.hpp>
+#include <bitcoin/bitcoin/settings.hpp>
 #include <bitcoin/bitcoin/math/hash.hpp>
 #include <bitcoin/bitcoin/utility/data.hpp>
 #include <bitcoin/bitcoin/utility/reader.hpp>
@@ -74,10 +75,10 @@ class BC_API header
 
     header(uint32_t version, const hash_digest& previous_block_hash,
         const hash_digest& merkle, uint32_t timestamp, uint32_t bits,
-        uint32_t nonce);
+        uint32_t nonce, const settings& settings);
     header(uint32_t version, hash_digest&& previous_block_hash,
         hash_digest&& merkle, uint32_t timestamp, uint32_t bits,
-        uint32_t nonce);
+        uint32_t nonce, const settings& settings);
 
     // Operators.
     //-------------------------------------------------------------------------
@@ -179,6 +180,7 @@ class BC_API header
     uint32_t timestamp_;
     uint32_t bits_;
     uint32_t nonce_;
+    const settings& settings_;
 };
 
 } // namespace chain

include/bitcoin/bitcoin/constants.hpp

@@ -95,31 +95,6 @@ BC_CONSTEXPR uint32_t relative_locktime_mask = 0x0000ffff;
 BC_CONSTEXPR uint32_t relative_locktime_disabled = 0x80000000;
 BC_CONSTEXPR uint32_t relative_locktime_time_locked = 0x00400000;
 
-// Timespan constants.
-//-----------------------------------------------------------------------------
-
-BC_CONSTEXPR uint32_t retargeting_factor = 4;
-BC_CONSTEXPR uint32_t easy_spacing_seconds = 20 * 60;
-BC_CONSTEXPR uint32_t target_spacing_seconds = 10 * 60;
-BC_CONSTEXPR uint32_t target_timespan_seconds = 2 * 7 * 24 * 60 * 60;
-BC_CONSTEXPR uint32_t timestamp_future_seconds = 2 * 60 * 60;
-BC_CONSTEXPR uint32_t retarget_proof_of_work_limit = 0x1d00ffff;
-BC_CONSTEXPR uint32_t no_retarget_proof_of_work_limit = 0x207fffff;
-BC_CONSTFUNC uint32_t work_limit(bool retarget=true)
-{
-    return retarget ? retarget_proof_of_work_limit : no_retarget_proof_of_work_limit;
-}
-
-// The upper and lower bounds for the retargeting timespan.
-BC_CONSTEXPR uint32_t min_timespan =
-    target_timespan_seconds / retargeting_factor;
-BC_CONSTEXPR uint32_t max_timespan =
-    target_timespan_seconds * retargeting_factor;
-
-// The target number of blocks for 2 weeks of work (2016 blocks).
-BC_CONSTEXPR size_t retargeting_interval =
-    target_timespan_seconds / target_spacing_seconds;
-
 // Fork constants.
 //-----------------------------------------------------------------------------
 

include/bitcoin/bitcoin/message/header.hpp

@@ -52,10 +52,10 @@ class BC_API header
     header();
     header(uint32_t version, const hash_digest& previous_block_hash,
         const hash_digest& merkle, uint32_t timestamp, uint32_t bits,
-        uint32_t nonce);
+        uint32_t nonce, const settings& settings);
     header(uint32_t version, hash_digest&& previous_block_hash,
         hash_digest&& merkle, uint32_t timestamp, uint32_t bits,
-        uint32_t nonce);
+        uint32_t nonce, const settings& settings);
     header(const chain::header& other);
     header(chain::header&& other);
     header(const header& other);

include/bitcoin/bitcoin/settings.hpp

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) 2011-2018 libbitcoin developers (see AUTHORS)
+ *
+ * This file is part of libbitcoin.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef LIBBITCOIN_SETTINGS_HPP
+#define LIBBITCOIN_SETTINGS_HPP
+
+#include <bitcoin/bitcoin/define.hpp>
+
+#include <cstdint>
+#include <cstddef>
+
+namespace libbitcoin {
+
+/// Common database configuration settings, properties not thread safe.
+class BC_API settings
+{
+
+private:
+    uint32_t retargeting_factor_;
+    uint32_t target_spacing_seconds_;
+
+public:
+    settings();
+
+    uint32_t easy_spacing_seconds;
+    uint32_t timestamp_future_seconds;
+    uint32_t target_timespan_seconds;
+    uint32_t retarget_proof_of_work_limit;
+    uint32_t no_retarget_proof_of_work_limit;
+
+    // The upper and lower bounds for the retargeting timespan.
+    uint32_t min_timespan;
+    uint32_t max_timespan;
+
+    // The target number of blocks for 2 weeks of work (2016 blocks).
+    size_t retargeting_interval;
+
+    uint32_t work_limit(bool retarget=true) const
+    {
+        return retarget ? retarget_proof_of_work_limit : no_retarget_proof_of_work_limit;
+    }
+
+};
+
+} // namespace libbitcoin
+
+#endif