It is redundant to store 'hash' and 'compare' function pointers in
struct Hashmap separately. The functions always comprise a pair.
Store a single pointer to struct hash_ops instead.
systemd keeps hundreds of hashmaps, so this saves a little bit of
memory.
The bitmask is deprecated in the kernel, so move to the new interface. At the moment
this does not make a difference for us, but it avoids having to change the API in the future.
Rather than allocating/freeing memory for each message read, keep a global read buffer
in the rtnl object. Also, rather than using a fixed size, peek at the pending message
header to get the message size and reallocate as necessary.
The object is not currently used, so just drop the refenence. If/when we end up
using the object in the future, we must make sure to deal with possible mutual
references between rtnl busses and their queued messages; as is done in sd-bus.
Extend rta_offset_tb into a stack of offset tables, one for each parent of the
current container, and make sd_rtnl_message_{enter,exit}_container() pop/push
to this stack.
Also make sd_rtnl_message_rewind() parse the top-level container, and use this
when reading a message from the socket.
This changes the API by dropping the now redundant sd_rtnl_message_read()
method.
Like sd-bus, sd-rtnl can have self-references through queued messages. In
particular, each queued message has the following self-ref loop:
rtnl->wqueue[i]->rtnl == rtnl
Same is true for "rqueue".
When sd_rtnl_unref() gets called, we must therefore make sure we correctly
consider each self-reference when deciding to destroy the object. For each
queued message, there _might_ be one ref. However, rtnl-messages can be
created _without_ a bus-reference, therefore we need to verify the
actually required ref-count.
Once we know exactly how many self-refs exist, and we verified none of the
queued messages has external references, we can destruct the object.
We must immediately drop our own reference, then flush all queues and
destroy the bus object. Otherwise, each sd_rtnl_message_unref() call would
recurse into the same destruction logic as they enter with the same
rtnl-refcnt.
Note: We really should verify _all_ queued messages have m->rtnl set to
the bus they're queued on. If that's given, we can change:
if (REFCNT_GET(rtnl->n_ref) <= refs)
to
if (REFCNT_GET(rtnl->n_ref) == refs)
and thus avoid recalculating the required refs for each message we
remove from the queue during destruction.
safe_close() automatically becomes a NOP when a negative fd is passed,
and returns -1 unconditionally. This makes it easy to write lines like
this:
fd = safe_close(fd);
Which will close an fd if it is open, and reset the fd variable
correctly.
By making use of this new scheme we can drop a > 200 lines of code that
was required to test for non-negative fds or to reset the closed fd
variable afterwards.
Previously the returned object of constructor functions where sometimes
returned as last, sometimes as first and sometimes as second parameter.
Let's clean this up a bit. Here are the new rules:
1. The object the new object is derived from is put first, if there is any
2. The object we are creating will be returned in the next arguments
3. This is followed by any additional arguments
Rationale:
For functions that operate on an object we always put that object first.
Constructors should probably not be too different in this regard. Also,
if the additional parameters might want to use varargs which suggests to
put them last.
Note that this new scheme only applies to constructor functions, not to
all other functions. We do give a lot of freedom for those.
Note that this commit only changes the order of the new functions we
added, for old ones we accept the wrong order and leave it like that.
The "sd_" prefix is supposed to be used on exported symbols only, and
not in the middle of names. Let's drop it from the cleanup macros hence,
to make things simpler.
The bus cleanup macros don't carry the "sd_" either, so this brings the
APIs a bit nearer.
