* The compiler can provide many non-explicit constructors for
aggregate types. This is sometimes desired, but it can
happen accidentally, resulting in run-time errors.
* This commit assures that no types are aggregates unless existing
code is using aggregate initialization.
Replace Taker.cpp with calls to the payment flow() code.
This change required a number of tweaks in the payment flow code.
These tweaks are conditionalized on whether or not offer crossing
is taking place. The flag is explicitly passed as a parameter to
the flow code.
For testing, a class was added that identifies differences in the
contents of two PaymentSandboxes. That code may be reusable in
the future.
None of the Taker offer crossing code is removed. Both versions
of the code are co-resident to support an amendment cut-over.
The code that identifies differences between Taker and Flow offer
crossing is enabled by a feature. That makes it easy to enable
or disable difference logging by changing the config file. This
approach models what was done with the payment flow code. The
differencing code should never be enabled on a production server.
Extensive offer crossing unit tests are added to examine and
verify the behavior of corner cases. The tests are currently
configured to run against both Taker and Flow offer crossing.
This gives us confidence that most cases run identically and
some of the (few) differences in behavior are documented.
* Sanity check on newly created strands
* Better loop detection
* Better tests (test every combination of path element pairs)
* Disallow any root issuer (even for xrp)
* Disallow compount element typs in path
* Issue was not reset when currency was XRP
* Add amendment
The Ripple protocol represent transfer rates and trust line
qualities as fractions of one billion. For example, a transfer
rate of 1% is represented as 1010000000.
Previously, such rates where represented either as std::uint32_t
or std::uint64_t. Other, nominally related types, also used an
integral representation and could be unintentionally substituted.
The new Rate class addresses this by providing a simple, type
safe alternative which also helps make the code self-documenting
since arithmetic operations now can be clearly understood to
involve the scaling of an amount by a rate.
The Owner count could decrease while evaluating a strand, causing
different behavior in forward passes and reverses passes. The fix treats
a decreased owner count like a deferred credit.
In some situations, deferred credits could cause an XRP balance to be
calculated as negative, triggering some asserts.
When XRP is used as a bridge currency, a path could be falsely marked as
dry. This happens when the XRP/XXX offer recursively checks the XXX/XRP
offer and the XXX/XRP offer could not satisfy the request in a single
call.
With a single strand and limit quality the old payment code incorrectly
computed with multiquailty set to true. This could cause the total
quality to go below the requested quality even if there was liquidity
available above the requested quality value.
Before this change, the deferred credits algorithm took the current
balance and subtracted the recorded credits. Conceptually, this is the
same as taking the original balance, adding all the credits,
subtracting all the debits, and subtracting all the credits. The new
algorithm records the original balance and subtracts the debits. This
prevents errors that occur when the original balance and the recorded
credits have large differences in magnitude.
Additionally, XRP credits were recorded incorrectly in the deferred
credits table (the line was between the sender and receiver, rather than
the root account).
Payments do not remove unfunded and expired offers when a payment
fails. However, offer crossing is now using the payment engine and needs
to know what offers were found in a removable state, even on failure.
Replace Journal public data members with member function accessors
in order to make Journal lighter weight. The change makes a
Journal cheaper to pass by value.
Also add missing stream checks (e.g., calls to JLOG) to avoid
text processing that ultimately will not be stored in the log.
Add a new algorithm for finding the liquidity in a payment path. There
is still a reverse and forward pass, but the forward pass starts at the
limiting step rather than the payment source. This insures the limiting
step is completely consumed rather than potentially leaving a 'dust'
amount in the forward pass.
Each step in a payment is either a book step, a direct step (account to
account step), or an xrp endpoint. Each step in the existing
implementation is a triple, where each element in the triple is either
an account of a book, for a total of eight step types.
Since accounts are considered in pairs, rather than triples, transfer
fees are handled differently. In V1 of payments, in the payment path
A -> gw ->B, if A redeems to gw, and gw issues to B, a transfer fee is
changed. In the new code, a transfer fee is changed even if A issues to
gw.
