DEX create password, DCR wallet and add server

[song50119]

Work towards #619

• Initialize app password
• Add wallet for dcr to use to pay the dex server fee
• Add dex server this come before adding any wallet
• Show the fee confirmations

Test server: dex-test.ssgen.io:7232

[itswisdomagain]

Looks good and works well. Major change required is connecting a DEX before connecting a wallet to pay fees. Also, if there are no plans to add assets aside dcr and btc for now, no need to initialize them or add their icons.

While reviewing, I tinkered with some of the requested changes and made a commit here for your perusal: itswisdomagain@5bcef82

[itswisdomagain]

Almost there. Just a few nits from me now.

[itswisdomagain]

Looks good to go from my end. Just one more possible improvement.

[itswisdomagain]

I have this issue with fee payments sometimes not getting broadcasted until godcr restart. Occasionally, I see the following error logs after paying the dex fee but the fee tx may still not be broadcasted even if there is no error log:

2021-10-29 09:33:43.025 [INF] DLWL: Inserting unconfirmed transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751
2021-10-29 09:33:43.105 [INF] DLWL: [1] New Transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751
2021-10-29 08:33:43.267 [INF] CORE: notify: |SUCCESS| (feepayment) Fee payment in progress - Waiting for 1 confirmations before trading at dex-test.ssgen.io:7232
2021-10-29 09:33:43.827 [WRN] DLWL: 47.242.243.123:19108 reject(tx, REJECT_INSUFFICIENTFEE, b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751): transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751 has insufficient priority (6.32261967816092e+06 <= 5.76e+07)
2021-10-29 09:33:43.925 [WRN] DLWL: 116.62.229.19:19108 reject(tx, REJECT_INSUFFICIENTFEE, b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751): transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751 has insufficient priority (6.32261967816092e+06 <= 5.76e+07)

In all cases though, I see

2021-10-29 09:33:43.025 [INF] DLWL: Inserting unconfirmed transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751
2021-10-29 09:33:43.105 [INF] DLWL: [1] New Transaction b90cdf32172c7e699be17ac9728d77671dbbd33cdaf58f515c315063f772e751

but the tx may not show up on dcrdata until godcr is restarted.

My guess is the dex is using a too little miners fee for the dex fee tx which causes it to be rejected by spv peers until godcr restart where dcrlibwallet/dcrwallet resends pending transactions. Confirming this theory will require constructing and sending raw transactions with small fees using dcrlibwallet, to see if the sent transaction gets indexed by dcrlibwallet but isn't found on dcrdata.

UPDATE:
A couple godcr restarts later, fee tx isn't on dcrdata still. Reset and re-connected the dex a couple times, same issue, restarting godcr that had fixed this for me isn't working now. I think this is the issue you had one time @song50119, where your dex fee remained at 0 confs for quite some time.

[itswisdomagain]

Just one more change requirement from me. I had tried to test what happens after the fee is confirmed but was unable to because multiple fee payment attempts had their transactions rejected and thus never confirmed. I've tested it now and it doesn't work quite well.

One additional thing, once any modal is displayed on the dex page, the rest of the app cannot be used until the user completes what's required by the modal. For a new dex user, that would require initializing the app, adding a DEX, adding a wallet and paying the fee before the modals disappear and the user can use the rest of the godcr app. Consider adding a close [x] button to each modal or allowing the modals to be closed by clicking outside them.

[Sirmorrison]

I believe we need more detailed description on this PR... Reason is i see a few unrelated changes to the issue addressed here.

Like appCTX dex initializing a db on godcr etc.

Also, details on how this PR can be properly tested.

[itswisdomagain]

i see a few unrelated changes to the issue addressed here.
Like appCTX dex initializing a db on godcr etc.

Both those changes re appCTX and additional db are part of the DEX client initialization process. I think that initial setup is missing in the PR description, although it might also be too granular to include.

This PR uses a couple dcrdex packages to provide DEX client functionality. The primary package for this purpose is decred.org/dcrdex/client/core which provides methods for initializing the client, adding wallets, placing and canceling orders and executing trades. Once decred.org/dcrdex/client/core is started, a number of background processes may run simultaneously. When starting core, a ctx is required that will be used to signal to core when all processes should shutdown. This context cannot be a random context.Background() but a context that actually gets canceled when the GoDCR app is shutting down; this signals core to also shutdown its activities. That's why the appCtx was introduced. In all honesty though, there should have been an appCtx running around somewhere to ensure pages are closed, background processes stopped when the godcr app is shut down; instead of using context.Background() as I've seen in a couple portions of this codebase.

As explained in a comment above, core needs to maintain its own database to function effectively. The DEX client is a pretty big app on its own and most of the work being done on the GoDCR end will be providing the interface to perform DEX functionality using core behind the scene.

[Sirmorrison]

i see a few unrelated changes to the issue addressed here.
Like appCTX dex initializing a db on godcr etc.

Both those changes re appCTX and additional db are part of the DEX client initialization process. I think that initial setup is missing in the PR description, although it might also be too granular to include.

This PR uses a couple dcrdex packages to provide DEX client functionality. The primary package for this purpose is decred.org/dcrdex/client/core which provides methods for initializing the client, adding wallets, placing and canceling orders and executing trades. Once decred.org/dcrdex/client/core is started, a number of background processes may run simultaneously. When starting core, a ctx is required that will be used to signal to core when all processes should shutdown. This context cannot be a random context.Background() but a context that actually gets canceled when the GoDCR app is shutting down; this signals core to also shutdown its activities. That's why the appCtx was introduced. In all honesty though, there should have been an appCtx running around somewhere to ensure pages are closed, background processes stopped when the godcr app is shut down; instead of using context.Background() as I've seen in a couple portions of this codebase.

As explained in a comment above, core needs to maintain its own database to function effectively. The DEX client is a pretty big app on its own and most of the work being done on the GoDCR end will be providing the interface to perform DEX functionality using core behind the scene.

Valid point.. however, i believe dcrlibwallet is designed for this. We can pass any required parameter to the calling function from the lib.

dcrwallet, VSPD etc operate almost like dex.

[Sirmorrison]

The dex button is always active... You need to use the inactive icon until the dex tab is selected.

[Sirmorrison]

• When the Dex page is selected, the button is still the inactive button. not Active. (I have asked the UI/UX guys to get us the logo).
• Also, When the dex page is opened, is shows password form. My recommendation will be to have a dex welcome describing what dex is about, and then a button for customer proceed. When the button is pressed, the create password modal is shown and the set up process follow. if the modal cancel button is pressed, we remain on the dex welcome page.

This just a proof of concept, however, if this is merged, it will be part of the next prerelease and as such, should look presentable on the app.

[Sirmorrison]

Link to the DEX icons https://www.figma.com/file/e0cYaAzkXyXXPY00v23cQY/GoDCR?node-id=452%3A90904

[itswisdomagain]

While we're here, a minor improvement.