Merge pull request #6958

9c3ee3b [doc] Add -maxuploadtarget release notes (MarcoFalke)
b27e81f [net] Cleanup maxuploadtarget (MarcoFalke)

5 files changed, 27 insertions, 5 deletions

diff --git a/doc/release-notes.md b/doc/release-notes.md
index 31704ba47c..2e9cc16940 100644
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -168,6 +168,25 @@ a connection to Tor can be made. It can be configured with the `-listenonion`,
 `-torcontrol` and `-torpassword` settings. To show verbose debugging
 information, pass `-debug=tor`.
 
+Reduce upload traffic
+---------------------
+
+A major part of the outbound traffic is caused by serving historic blocks to
+other nodes in initial block download state.
+
+It is now possible to reduce the total upload traffic via the `-maxuploadtarget`
+parameter. This is *not* a hard limit but a threshold to minimize the outbound
+traffic. When the limit is about to be reached, the uploaded data is cut by not
+serving historic blocks (blocks older than one week).
+Moreover, any SPV peer is disconnected when they request a filtered block.
+
+This option can be specified in MiB per day and is turned off by default
+(`-maxuploadtarget=0`).
+The recommended minimum is 144 * MAX_BLOCK_SIZE (currently 144MB) per day.
+
+A more detailed documentation about keeping traffic low can be found in
+[/doc/reducetraffic.md](/doc/reducetraffic.md).
+
 0.12.0 Change log
 =================
 
diff --git a/qa/rpc-tests/maxuploadtarget.py b/qa/rpc-tests/maxuploadtarget.py
index 67c4a50985..148c5f37e4 100755
--- a/qa/rpc-tests/maxuploadtarget.py
+++ b/qa/rpc-tests/maxuploadtarget.py
@@ -192,7 +192,8 @@ class MaxUploadTest(BitcoinTestFramework):
         getdata_request.inv.append(CInv(2, big_old_block))
 
         max_bytes_per_day = 200*1024*1024
-        max_bytes_available = max_bytes_per_day - 144*1000000
+        daily_buffer = 144 * 1000000
+        max_bytes_available = max_bytes_per_day - daily_buffer
         success_count = max_bytes_available / old_block_size
         
         # 144MB will be reserved for relaying new blocks, so expect this to
diff --git a/src/init.cpp b/src/init.cpp
index 87a23deab7..a83a136fa5 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -375,7 +375,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-whitebind=<addr>", _("Bind to given address and whitelist peers connecting to it. Use [host]:port notation for IPv6"));
     strUsage += HelpMessageOpt("-whitelist=<netmask>", _("Whitelist peers connecting from the given netmask or IP address. Can be specified multiple times.") +
         " " + _("Whitelisted peers cannot be DoS banned and their transactions are always relayed, even if they are already in the mempool, useful e.g. for a gateway"));
-    strUsage += HelpMessageOpt("-maxuploadtarget=<n>", strprintf(_("Tries to keep outbound traffic under the given target (in MiB per 24h), 0 = no limit (default: %d)"), 0));
+    strUsage += HelpMessageOpt("-maxuploadtarget=<n>", strprintf(_("Tries to keep outbound traffic under the given target (in MiB per 24h), 0 = no limit (default: %d)"), DEFAULT_MAX_UPLOAD_TARGET));
 
 #ifdef ENABLE_WALLET
     strUsage += HelpMessageGroup(_("Wallet options:"));
@@ -1193,7 +1193,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     }
 #endif
     if (mapArgs.count("-maxuploadtarget")) {
-        CNode::SetMaxOutboundTarget(GetArg("-maxuploadtarget", 0)*1024*1024);
+        CNode::SetMaxOutboundTarget(GetArg("-maxuploadtarget", DEFAULT_MAX_UPLOAD_TARGET)*1024*1024);
     }
 
     // ********************************************************* Step 7: load block chain
diff --git a/src/net.cpp b/src/net.cpp
index ada4a1bb62..1ea50b2493 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2117,8 +2117,8 @@ void CNode::SetMaxOutboundTarget(uint64_t limit)
     uint64_t recommendedMinimum = (nMaxOutboundTimeframe / 600) * MAX_BLOCK_SIZE;
     nMaxOutboundLimit = limit;
 
-    if (limit < recommendedMinimum)
-        LogPrintf("Max outbound target is very small (%s) and will be overshot. Recommended minimum is %s\n.", nMaxOutboundLimit, recommendedMinimum);
+    if (limit > 0 && limit < recommendedMinimum)
+        LogPrintf("Max outbound target is very small (%s bytes) and will be overshot. Recommended minimum is %s bytes.\n", nMaxOutboundLimit, recommendedMinimum);
 }
 
 uint64_t CNode::GetMaxOutboundTarget()
diff --git a/src/net.h b/src/net.h
index d89244523e..cd2d225d73 100644
--- a/src/net.h
+++ b/src/net.h
@@ -60,6 +60,8 @@ static const bool DEFAULT_UPNP = false;
 static const size_t MAPASKFOR_MAX_SZ = MAX_INV_SZ;
 /** The maximum number of peer connections to maintain. */
 static const unsigned int DEFAULT_MAX_PEER_CONNECTIONS = 125;
+/** The default for -maxuploadtarget. 0 = Unlimited */
+static const uint64_t DEFAULT_MAX_UPLOAD_TARGET = 0;
 
 unsigned int ReceiveFloodSize();
 unsigned int SendBufferSize();