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sqlite: Initial port #417

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@msdx321 msdx321 commented Mar 18, 2021

Summary of this Pull Request (PR)

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Intent for your PR

Choose one (Mandatory):

  • This PR is for a code-review and is intended to get feedback, but not to be pulled yet.
  • This PR is mature, and ready to be integrated into the repo.

Reviewers (Mandatory):

(Specify @<github.com username(s)> of the reviewers. Ex: @user1, @user2)

Code Quality

As part of this pull request, I've considered the following:

Style:

  • Comments adhere to the Style Guide (SG)
  • Spacing adhere's to the SG
  • Naming adhere's to the SG
  • All other aspects of the SG are adhered to, or exceptions are justified in this pull request
  • I have run the auto formatter on my code before submitting this PR (see doc/auto_formatter.md for instructions)

Code Craftsmanship:

  • I've made an attempt to remove all redundant code
  • I've considered ways in which my changes might impact existing code, and cleaned it up
  • I've formatted the code in an effort to make it easier to read (proper error handling, function use, etc...)
  • I've commented appropriately where code is tricky
  • I agree that there is no "throw-away" code, and that code in this PR is of high quality

Testing

I've tested the code using the following test programs (provide list here):

  • micro_booter
  • unit_pingpong
  • unit_schedtests
  • ...(add others here)

msdx321 added 5 commits March 19, 2021 00:33
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
@@ -31,7 +34,7 @@ libc_syscall_override(cos_syscall_t fn, int syscall_num)
cos_syscalls[syscall_num] = fn;
}

struct sl_lock stdout_lock = SL_LOCK_STATIC_INIT();
//struct sl_lock stdout_lock = SL_LOCK_STATIC_INIT();
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Is there demand for a single threaded version of this? Removing all this synchronization logic is going to lead to weird bugs as soon as you have more than one thread. Why doesn't it work as-is? Too tight coupling to SL?

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Great question, and good intuition. We revamping libposix right now to use a generic interface that can either be co-located (via library) with sl, or accessed in another component. Given this, most of the synchronization facilities (and sl dependencies) in posix need to change backing APIs.

As such, Bite is trying to get sqlite working for a comparison case, and is not trying to solve other problems for now. As we update posix, I'm hoping we can add back in those features.

A lot of the cruft assuming single-component runtimes has been removed, but we have more to do, and libposix is one of the big places more love needs to be applied.

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I think that a lot of your changes are in the sqlite repo. How do you want to proceed with that. See my comment about having a main branch that tracks sqlite's upstream.

Some comments about how to avoid losing all of the sync and futex code.

@@ -4,3 +4,6 @@
[submodule "src/components/lib/ck/ck"]
path = src/components/lib/ck/ck
url = https://github.com/gwsystems/ck.git
[submodule "src/components/lib/sqlite/sqlite"]
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You'll want to move this into gwsystems. Remember, we want the main branch of the repo be unmodifed, and have a cos branch that we pull in as a submodule. That way we have a path for updating the code as upstream changes.

@@ -0,0 +1,9 @@
## tests

This is the skeleton interface used by the `mkcomponent.sh` script to aid in the creation of a new component.
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Add documentation here, or remove the file.

{
}

int result_print(void *v, int argc, char **argv,
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your line width wraparound seems too aggressive. I don't think that the argument needs to be on another line.

#include <cos_defkernel_api.h>

void
cos_init(void)
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If you remove this function, it should still work. If you don't have code in it, remove it!

int
main(void)
{
printc("Calling sqlite functions\n");
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inconsistent indentation styules. likely mixing spaces and tabs.

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variable definitions should be at the top of the block.

completed_successfully = sl_thd_block_timeout(0, wakeup_deadline);
wakeup_time = sl_now();
//wakeup_deadline = sl_now() + sl_usec2cyc(time_to_microsec(req));
wakeup_deadline = 0;
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I don't think that silently failing is the best policy here. We should probably fail loudly if a function that we don't support is called. BUG(), assert(0), after a printc to explain. etc...

I don't trust client checking for ENOTSUP which would be the normal solution. Failure is more appropriate if it isn't supported here.

@@ -263,23 +272,27 @@ cos_set_tid_address(int *tidptr)
* };
*/

void* backing_data[SL_MAX_NUM_THDS];
//void* backing_data[SL_MAX_NUM_THDS];
void* backing_data[1];
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COS_NUM_THREADS, I think???

@@ -291,11 +304,13 @@ cos_clone(int (*func)(void *), void *stack, int flags, void *arg, pid_t *ptid, v
return -1;
}

struct sl_thd * thd = sl_thd_alloc((cos_thd_fn_t) func, arg);
//struct sl_thd * thd = sl_thd_alloc((cos_thd_fn_t) func, arg);
struct sl_thd * thd = 0;
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This shouldn't compile, right? Where is the defn of sl_thd coming from here?

assert(0);
}

/* TODO: Cleanup empty futexes */

struct sl_lock futex_lock = SL_LOCK_STATIC_INIT();
//struct sl_lock futex_lock = SL_LOCK_STATIC_INIT();

/*
* precondition: futex_lock is taken
*/
int
cos_futex_wait(struct futex_data *futex, int *uaddr, int val, const struct timespec *timeout)
{
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This is all pretty challenging logic that Gregor spent a lot of time on. What I'd like: create an issue with a link to the commit in which this is removed, so that we can know how to easily bring back this code when hook up posix to the rest of the system.

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I think there have to be ways to do this that don't sacrifice correctness. (ie that fault instead of being unsafe concurrently) I'm always nervous leaving things in a subtly broken state--it's easy to forget the exact brokenness and put yourself in debugging hell for no reason later

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Great point.

Perhaps we replace the current lock implementation with something that simply errors out on contention:

struct lock {
        unsigned long owner;
};
struct lock global_lock = (struct lock) { .owner = 0 };
void
lock_take(void) {
        // failure here indicates that you're using concurrency/parallelism, which posix doesn't yet support!
        if (!ps_cas(&global_lock.owner, 0, cos_thdid())) assert(0);
}
void
lock_release(void) {
        // failure here indicates unpaired take and release.
        assert(global_lock.owner == cos_thdid());
        ps_store(&global_lock.owner, 0);
}

Replace normal lock behavior which requires contention management with simple "error out".

@@ -0,0 +1,9 @@
## sqlite

This is the skeleton library used by the `mklib.sh` script to aid in the creation of a new library.
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documentation or remove.

msdx321 added 17 commits August 9, 2021 11:05
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
Signed-off-by: msdx321 <msdx321@gmail.com>
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3 participants